ASUS HD6990 4GB Graphics Card Review

The Asus HD6990 promises to be a graphics card to satisfy even the most power hungry gamer. Join us as we give the AMD flagship card the Vortez treatment…

Product on Review: Asus HD6990
Manufacturer and Sponsor: ASUS
Street Price: £524.03

ASUS are a household name among system builders and enthusiasts alike. They are without doubt one of the premier PC component manufacturers in today’s market and because of this reputation, you can expect quality and service that is second to none.

Their flagship AMD graphics card on test today is the stunning HD6990, a dual GPU core model hosting a huge 4GB of GDDR5. Some might argue that there is simply no need for such a GPU, that graphics cards of this nature are for bragging rights only and are simply built to serve those with more money than sense. Others argue that this card should not be classed as a single graphics card. Whichever your interpretation, both AMD and NVidia have both released various incarnations of multi GPU cards, some being of the dual PCB ‘sandwich’ type like the NVidia GX2 and early revisions of the GTX295, others having two GPUs on a single PCB like the AMD 4870×2, NVidia GTX590 and the HD6990’s forbear, the HD5970. The HD6990 is the latter of the two designs, incorporating two cores on a single power circuit board which is now the standard format for dual GPU design.

Two cores will require more power, emit more heat and this usually translates to more noise to keep that heat under control. Previous designs had received negative feedback because the noise the cards make were very loud, often so much so that they were very intrusive when using them for what they were designed for, gaming. The card we have today is of a reference design and as such it remains to be seen whether the cooler has been adapted to create less of a din than previous editions. We will certainly be closely examining the cooler and acoustics of the card to see what innovations, if any, have taken place.

About ASUS

ASUS comes from the last four letters of Pegasus, the winged horse in Greek mythology that represents the inspiration of art and learning. ASUS embodies the strength, creative spirit and purity symbolized by this regal and agile mythical creature, soaring to new heights of quality and innovation with each product it introduces to the market. ASUS pursues technological and aesthetic perfection through continuous innovation. We place ourselves in our customers’ shoes to develop a deep understanding of, and genuine empathy for, their needs—enabling us to create user experiences that transcend the norm. ASUS Design Philosophy ASUS Design develops high-quality solutions our customers will enjoy. Our design process is built on thorough research, early anticipation and well-planned execution. We act with a global vision and a focus on local strengths, conditions and heritage.

Let’s take a look at the specification of the card we have on test today…

Specification

Codenamed “Antilles”, the ASUS HD6990, much like other reference HD6990’s come equipped with two Cayman XT (VLIW4) cores, the same cores that make up the flagship cards siblings, the single GPU HD6970 and HD6950. Despite rumours of the HD6990 having to reduce its stream processor count to keep heat under control, the HD6990 has the full 1536 stream processors enabled per core. Each core is also married to 2GB of GDDR5 (4GB total), courtesy of Hynix.

With the optional AWSUM (read Awesome) feature disabled (more on this later), the cores are clocked at an impressive stock speed of 830MHz and while this is lower than the stock HD6970 single corespeed of 880MHz you have to bear in mind that with two of the cores running at an albeit lower clockspeed, they will kick out a serious amount of heat. Also running lower than the HD6970 is the memory speed which is set to 5GHz rather than 5.5GHz (effective). Slower speeds however are however more than compensated because of double the processing power and memory.

Considering that when in stock form this card will consume a very thirsty 375W, it is understandable that AMD have seen fit to lower the clockspeeds of both the 4GB of GDDR5 and the two Cayman XT cores. However, if you have a beefy PSU you can enable the AUSUM switch which will raise the clocks and inevitably the power consumption to an incredible 450W, breaking the PCIe specification. AMDs caveat to this infringement is to place a very large yellow sticker over the AUSUM switch, warning of the End of Days and the coming Apocalypse so to use at your own discretion. If like me, you never heed such warnings you will void the warranty of the card which could prove a very expensive mistake being that the card is retailing for around the £500 mark!

The PCIe guidelines make a recommendation that 300W is the safe maximum a card should draw from the PSU with an additional 75w being provided by the PCIe slot. As you can see in stock form the HD6990 is bang on the money for stock speed power consumption but hitting the AUSUM switch will mean that figure is increased by a potential 75w draw from the 2x 8pin PCIe power sockets with a combined draw of 450W through the 12v rail(s) of a PSU for graphics power alone!

Product Specification

Product Code: 90-C3CH10-T0UAY0YZ
EAN Code: 4719543377024
Cooler: Stock
GPU: HD6990
Core Clock: 830 (880) MHz
Memory Clock: 5000 (5500) MHz
Memory Size: 4096 MB
Memory Type: GDDR5
Memory Interface: 256 bit
Memory Bandwidth: 320GB/s
Interface: PCI Express x16 (PCI Express 2.1)

Let’s take a look at the cards features…

Features

Get Immersed with AMD Eyefinity Technology
•Enable ultra-high resolution multi-monitor gaming with 2GB of high speed GDDR5 memory.
•Expand your favourite games across up to 4 displays with AMD Eyefinity technology for an expansive field of view.
•See more of the battle than ever before with up to 4 simultaneous displays.
•Get the freedom and flexibility to upgrade. This modular solution enables you to add additional displays.
•Put your productivity into overdrive and let up to 4 displays put all the information you need right before your eyes.
•Don’t choose between play and work. Let up to 4 displays help you enjoy games, movies and the web at the same time.

Get Amazing EyeDefinition Graphics with DirectX 11 Technology
•New and advanced architecture featuring full DirectX® 11 support and scalable geometry processing.
•Featuring a new and advanced architecture with scalable geometry processing, the AMD Radeon HD™ 6900 Series is purpose-built to dominate your games.
•Maximum efficiency & performance. AMD PowerTune technology puts exceptionally intelligent power management under your control.
•Raise the bar for beautifully smooth image quality with Enhanced Quality Anti-Aliasing (EQAA).
•Dual advanced programmable tessellation engines for twice the geometry processing performance of previous generations.
•Play your favourite games in full stereo 3D, and get incredibly rich and interactive gameplay with AMD HD3D technology.

Speed Up Applications and Enjoy Brilliant Video with AMD EyeSpeed Technology
•Unleash the most demanding applications with AMD Accelerated Parallel Processing (APP) technology.
•Supports double precision floating point arithmetic to handle computationally intense workloads.
•Smooth visual quality with AMD EyeSpeed visual acceleration technology.
•Experience Blu-ray 3D as it was intended with AMD HD3D technology.
•Take advantage of AMD Radeon™ HD 6900 Series graphics’ Dolby TrueHD and 3D HDTV support.

Put out Stunning Visual and Unrivalled Audio Experience with HD3D Technology
•Stereo 3D display/glasses support
•Stereo 3D gaming
•Blu-ray™ 3D support
•3rd Party stereo 3D middleware software support
•Launching with AMD Radeon™ 6900 Series GPUs

Microsoft® DirectX® 11 Support
Get intense gaming performance and unrivalled image quality with stunning 3D visual effects, realistic lighting and lifelike imagery, driven by a new and advanced DirectX® 11-capable architecture with scalable geometry processing.

AMD Eyefinity Technology
Enjoy the ultimate immersive gaming experience with AMD’s Eyefinity multi-display capabilities.

AMD Advanced Parallel Processing technology
Accelerate the most demanding applications for improved performance.

Advanced GDDR5 Memory Technology
Delivers more speed and higher bandwidth.

AMD CrossFireX™ Technology
Increase your gaming performance with AMD CrossFireX™ Technology.

3rd Generation TeraScale Engine
Provides increased processing power for the latest games and accelerated applications.

40nm Process Technology
Provides enhanced processor performance while using less power and better transistor efficiency than previous generation technology.

Accelerated Video Transcoding
Helps improve video transcoding performance.

Display Flexibility
More flexibility with maximum connectivity for the latest display technologies.

HDMI 1.4
Helps ensure you get the full Blu-ray and PVR experience from your PC.

Dolly®TrueHD and DTS-HD Master Audio Support
Get a fully immersive high-definition audio experience with the latest Blu-ray movies.

AMD PowerPlay™ Technology
Power draw scales according to activity so when GPU activity is low, the power draw is minimal.

Enhanced Unified Video Decoder (UVD) 3Watch the hottest Blu-ray movies, online video and other HD content beyond 1080p with low power and low noise with GPU acceleration and enhanced Unified Video Decoder (UVD) 3 features.

ASUS exclusive features

Voltage Tweak – Full throttle overclocking with exclusive ASUS Voltage Tweak via Smart Doctor – boosting 50%* more speed, performance and satisfaction!

ASUS Smart Doctor – Intelligent system monitoring for efficient overclocking with an intuitive slide bar.

ASUS Gamer OSD – Real-time overclocking, benchmarking and video capturing in any PC game!

Splendid™ Video Intelligence Technology – Optimizes colors in various entertainment scenarios with five special modes — standard, game, scenery, night view and theater.

Packaging & Contents

The box front

The box is pretty much a standard affair with the familiar Dark knight dominating the front of the package, embossed onto a matt orange picturesque fantasy castle scene.

The box front features

The main feature ASUS appear keen to push is the Voltage Tweak ‘shift into overdrive’ option, claiming up to 50% faster clockspeeds. With the card already consuming 375W-450W, I am apprehensive to push the boundaries even further by using the Voltage Tweak feature but we will see what happens later in the review.

The box rear

Flipping the box over, we come to the rear of the box which has a full multi-lingual breakdown of the powerful features the HD6990 has to offer including 4GB of GDDR5, Variety connectivity, DX11 support along with ASUS’ own innovations mentioned on the features page of the review. Again, Voltage Tweak (do you really want us to destroy the card ASUS?) makes an appearance along with a and Eyefinity screenshot of what looks to be displaying Battlefield 3. This sits alongside a connectivity diagram. Sadly there was no copy of Battelfield 3 to be found in the package!

The system requirements

The bottom of the outer sleeve shows the system requirements/recommendations to run the HD6990 which are as follows: 3GB of system memory, free PCIe slot, Microsoft Windows XP/Vista/7,A minimum 700w power supply with a 12V current rating of 42A and 2 x 8pin PCIe PCI Express supplementary power connectors.

The inner box

Removing the outer sleeve leaves us with a quality corrugated cardboard inner box adorned with a golden ASUS logo. I must confess I have long been a fan of the ASUS style of packaging which is very neat, efficient and yet pleasing on the eye.

The accessories

Opening this inner box we were greeted with a further slimline box containing the accessories above which include: Driver and utilities CD inside a familiar ‘speed setup’ paper wallet, 1x dual 6pin to 8 pin PCIe power converter, 2 x Mini DP to DVI adapters and 1 x Mini DP to HDMI adapter.

The graphics card compartment

Finally after the Babushka style packaging we arive at the main box containing the card which is held very tightly by Styrofoam. The foam brace also has a little cutout containing a Crossfire bridge.

While the packaging is very neat and tidy and the accessories apt for a card of this nature, I was disappointed to find that there was no included game. For £500, I would at least have expected a good DX11 title to supplement the product but alas there was none which was a shame considering the thought that had gone into the rest of the product.

Let’s now take a look at the card itself…

Closer Look

The ASUS HD6990

First impressions are good, with the sleek black design of the reference cooler being the first thing to hit you. The accompanying bright red pin stripes are reminiscent of an 80’s sports car which isn’t a bad thing as it hints at the hidden power underneath the massive cooler. While the overall design is basic, I personally like the sleek, smart yet understated look rather than the gaudy stickers found on some. This certainly appears, at first glance anyway, to be a grown-ups card. The raised silver ASUS emblem adds to the overall aesthetics without detracting from the Monolith styling.

The ASUS HD6990 top

The card is a certainly a full fat model, measuring exactly 12 inches (30cm) long, just a few mm shorter than its predecessor, the HD5990 and weighing a touch over 1kg. So not only will you need a large PSU to run the card, you will need plenty of space to house one, not just in length but the card will also require two slots of motherboard real estate.

The ASUS HD6990 backplate

I’m usually the first to complain when a high end card arrives without a backplate, so I am pleased to report that the ASUS HD6990 arrives with a full length Aluminium plate measuring 1.5mm thick covering all the components bar the rear of the cores. The only items covering the backplate are two product stickers giving the product code and serial number. Interestingly there are also two rubber spacers glued to the front edges of the backplate, presumably to prevent two of the HD6990’s touching one another when in Crossfire mode as the backplate gets insanely hot when in use.

The ASUS HD6990 rear cooler bracket

The main backplate is held on with screws and as we shall see, sticky pads. While these screws attach to the main cooler, the cores have there own brackets to ensure good core contact and thereby even heat distribution. Each bracket is exposed and attached via four spring loaded screws and are relatively easy to remove should you have a small enough Phillips head screwdriver. While the majority of the power circuitry is shielded because of the main backplate, the core areas remain exposed so care is still required when installing the card.

The ASUS HD6990 cooling fan

The centre of the card is dominated by the fan. While this may seem like an odd place to put a fan it actually makes sense. With older X2 cards, the fan was at the end of the card meaning the 1st GPU got all the cool air and its brother was a wash with the formers hot exhaust air. This design draws air in through the centre and equally cools both cores. The downside to this is that inevitably hot air from one core will be expelled into the case.

Closer Look pt.2

The I/O Backplate

As the ASUS HD6990 is a reference design, it matches the AMD specification for display outputs. From left to right there are four mini-DisplayPort connectors and a single DL-DVI port supporting up to 2560×1600 single resolutions. The five connections allow five screens to be supported. Should you have a Multi-Stream Transport hub (MST), a sixth screen can be added to complete that Eyefinity setup you have dreamed of.

The internal vent

Because of the central fan design it would be unwise to have any components near the end of the card such as a hard drive as the card will vent hot exhaust air directly at it. Also please ensure your case cooling is up to scratch as this card kicks out a serious amount of heat, both from the I/O shield, the cards backplate and the internal vent at the end of the card.

The PCIe power sockets

Consuming 375W in stock form is going to need a very good power supply (700W minimum as recommended by ASUS) with 42.5A on the 12V rail. As you can see, the PCIe slot will need to be supplemented by a further two 8pin PCIe power cables. While the card accessories afford a dual 6pin to single 8pin connector you will still require the 2x 6pin PCIe cables and another free 8pin PCIe cable of your own to allow the card to run.

I find it impressive that while the HD6990 uses two 8pin Power power ports, a single HD6970 uses an 8 and a 6pin configuration so to power the card with just 2 additional pins is certainly a feat despite AMD breaking the PCI-SIG guidelines.

The Crossfire connector

Unfortunately, the HD6990 can only be twinned with another single card from the same family, be it a HD6990, HD6970 or HD6950 due to the single Crossfire header. That said it is extremely unlikely that you would have a power plant big enough to power more than that or indeed require more GPU processing power than a potentially 4 core setup can provide.

The ‘AUSUM’ switch

Previous incarnations of a physical, switchable BIOS switch were seen when the 6900 series first appeared on the scene. These BIOS switches enabled the end user to have a ‘stock’ BIOS and a further BIOS which could be edited by the user to setup the card how they wished. This time however, AMD have seen fit to pre-overclock a second BIOS on your behalf allowing you to run the card in either stock or overclocked formats. The stock speed of 830/5000 is attained in position 1 with a voltage set to 1.12v, while position 2 increases this voltage to 1.175v allowing the clockspeed to be raised to 880/5500.

The cautionary sticker protecting the switch is certainly needed as neither BIOS is write protected and both BIOS’ can be increased further to consume a potential 540w using the PowerTune limit via the Catalyst software. This will draw much more than the recommended 150w per PCIe cable from the PSU. Just be careful that you have adequate power supply and sufficient cooling otherwise I fear your expensive card and perhaps your PSU will go up in a puff of smoke should you alter the installed stock and pre-overclock settings. I will re-iterate that a good power supply is highly recommended when running this GPU.

Closer Look pt.3

Main cooler

ASUS have used a reference cooling design that encompasses all of the major components of the card. The two main GPU’s are cooled separately by Vapor chamber cooling heatsinks with full copper bases. The 8 GDDR5 memory modules along with the PCI-Express bridge chip are cooled by means of thermal tape, while the VRMs also have there own different type of thermal interface material. Everything bar the copper core cooling is attached to the internal Aluminium mid-plate with the separate GPU coolers having there own direct contact heatsinks screwed to the same mid-plate.

Backplate

Line the mid-plate, the backplate cools the other 2GB (8x 256mb) memory chips via thermal tape.

Thermal tape

The thermal tape is very sticky and can easily be removed and reapplied unlike the ceramic, flaky TIM used on NVidia cards. In our sample, all of the tape was very well aligned to the modules there were designed to cool ensure excellent surface contact.

Core TIM contact area

AMD have used a ‘special’ Phase Change based TIM to provide contact to the copper heatsink baseplate. AMD claim this TIM will provide exceptional contact to the cooler but once removed it is not re-usable. The consistency is fairly brittle and was very stubborn when being removed because of prior curing.

Vapor chamber

Each copper core is attached to a 37 finned vapor chamber, each independent of one another. The chambers are fairly rigid and not at all flimsy but I fear cleaning them out will prove difficult so a can of compressed air will be needed for maintenance.

Cooling fan

The cooling fan is of typical AMD design found on many reference cards. The fan will work by sucking cool air in from the centre of the card and exhausting it out either end via the I/O shield and internal vent. Aside from the prior comments about this nature of cooling, noise as we shall see, is another problem the card faces as most reference AMD heatsinks are akin to a leaf blower when running at full tilt.

Closer Look pt.4

HD6990 PCB top

Here we can see the card fully exposed and stripped of it its cooling. While the cores are framed by the memory modules in symmetry, the PCI Express bridge chip is slightly off centre to make way for the power regulators. Overall, the PCB is of very good quality with precise soldering throughout as you would expect.

HD6990 PCB rear

The rear of the card has the remaining 2GB of Hynix GDDR5 along with two voltage regulators, one for each core.

Power regulation

Here’s a close up shot of one of the Volterra VT1556MF PWM programmable regulators. Each core has one of these chips and is the staple controller for the 6900 family. Offering 12C communication and control, it provides all of the high level voltage regulation.

PCI-Express Bridge chip

The PCI-Express bridge chip is the same specification of the HD5970 which is also manufactured by PLX but still has the old ATI insignia, possibly because the chip is from the parts bin of previous graphics cards. This bridge chip is fully compliant with PCIe 2.1 x16 specification so can provide enough bandwidth per core regardless of the strain they are under.

Power inductors

Power delivery to the two Caymen XT cores comes courtesy of 8 ICs (4 phase to each core) hidden beneath the white stickered inductor shields. The memory modules get provided with 2 phase power circuitry while the PCI-Express bridge chip makes do with a single phase.

MOSFETs

The power from the inductors are then filtered by Cooper Bussmann chokes (above) who are one of the oldest, leading players in the power circuitry market having over 90 years experience in the business so you can be assured of quality.

Cayman XT core

Above is a shot of the Cayman core itself. Based on 40nm architecture, the core yields over 2.64 billion transistors on a die of just 389 mm². Like all previous AMD/ATI cards, the core is fully exposed and aside from the aluminium frame, it has no protection from misaligned coolers so please be careful if you intend to remove the cooler yourself.

Memory modules

The HD69900 comes equipped with 16x256mb Hynix GDDR5 modules totaling 4GB. The chips identification is H5GQ2H24MFR-T2C signifying that they are rated to 1250MHz (5000Mhz effective) when provided with 1.5v. It remains to be seen if this speed can be exceeded then as the AUSUM switch increases memory bandwidth to 5.5 GB/s.

With the technical furore out of the way, let’s now take a look at the bundled software of the ASUS HD6990…

Test Setup

We have recently made a slight amendment to our selection of hardware and our test setup. The reason for this is that we felt the current crop of resolutions were not stressing the latest generation of graphics cards enough. With this in mind, we have added a Dell 3007 WFP-HC to our system, allowing us to stress the cards by utilising a 2560×1600 resolution. We will however, still include 1920×1200 results as this is one of the most popular resolutions used by gamers.

Display – Dell 3007 WFP-HC
Case – Lian Li PC-P80
CPU Cooler – Prolimatech Super Mega (2xProlimatech 140mm Vortex)
CPU – Intel Core i7 920 @ 4GHz
RAM – 6GB (3x2GB) OCZ Blade DDR3 1600mhz 7-8-7-20 C1
Motherboard – ASUS Rampage III Extreme
Power Supply – Enermax Revolution 85+ 850W
Hard Drive – GSkill Falcon 128GB & Hitachi 250GB

Graphics Cards:

ASUS HD6990 @830/5000MHz & AWSUM enabled (pre-overclocked) 880/5500MHz & Further Overclock of 930/6000MHz – ATI Catalyst 11.5

HIS HD6970 2048MB IceQ Turbo @ 900/5600MHz Pre-overclocked & 1000/6000MHz Overclocked – ATI Catalyst 11.5
Gigabyte GTX560 1024MB @ 830/4008MHz & 841/5016MHz Overclocked – Forceware 275.27
MSI R6970 2048MB Lightning @ 940/5500MHz Pre-overclocked & 1010/6000MHz Overclocked – ATI Catalyst 11.4 (8.840.3.0)
Inno3D GTX560Ti 1024MB @ 820/4008MHz & 950/4300MHz Pre-overclocked –Forceware 266.66
Inno3D GTX570 1280MB @ 732/3800MHz, 800/4000MHz Pre-overclocked & 901/4220MHz Overclocked – Forceware 263.09
ASUS GTX580 1536MB @ 782/4000MHz & 903/4220MHz Overclocked – Forceware 262.99
ASUS HD6970 2048MB @ 890/5500MHz & 949/5896MHz Overclocked – ATI Catalyst 11.4 (8.840.3.0)

Driver versions are extremely important when comparing a graphics card. It is however often important to update a driver version, especially when a new GPU is released and thus any change in driver will be clearly stated.

Overclocking
For todays review we will use the Overdrive utility from the latest Catalyst 11.5 to overclock or test subject.

Games:
Crysis Warhead
Metro 2033
Dirt 3
Mafia II
Battlefield:Bad Company 2
Farcry 2
Alien vs. Predator

The games above represent equal bias toward both AMD and NVidia and are among the most demanding games available at present. Future releases will be evaluated for consistency and accuracy and then potentially added to the list when they become available

Synthetic benchmarks:
Futuremark 3DMark 11
Unigine Heaven 2.5
Tessmark 0.2.2
Furmark 1.9.0

Synthetic benchmarks are used to stress each feature of a GPU which may not be present in today’s games. While nothing is certain, the benchmarks above do at least give us an insight into the possible future performance of the graphics card on test, invaluable when evaluating the potential lifespan of a graphics card.

Temperature, power consumption and acoustics:
Furmark 1.9.0

The above application is feared by most manufacturers as it has been known to destroy GPU’s. While it is not indicative of ‘real world’ performance, it does represent the maximum possible stress your GPU could be placed under making it the hardest test to pass. For that reason alone, it is worthy of inclusion in our suite of benchmarks. Power consumption will be evaluated from the wall and will be a total system draw of the specification above.

Sound will be measured from a distance of 20 cm from the actual GPU with the case open. All system fans will be set to their lowest settings. Readings will be taken at both idle and 100% load.

Bundled Software

The Driver CD comes bundled with the typical ASUS suite found on most of their graphics cards accessory list. The included driver version is Catalyst version 11.2 but for the purposes of this review we will be using the latest official driver supplied from AMD, Catalyst 11.4.

The SmartDoctor application has been around for sometime now and for all intents and purposes has the same functionality of MSI’s Afterburner in that both clockspeeds of the memory and cores can be adjusted along with further voltage adjustments should you require to a maximum of 1.35v! This is achieved by means of a slider which is very accurate, rising in 0.001v increments. The GPU temperature is displayed in both Celcius and Fahrenheit. Fan speed can also be seen (though not adjusted) on a separate tab. To adjust fan speed you have to delve deeper into the settings. Apply and reset buttons are found beneath the monitoring screen adjacent to the settings button.

Pressing the settings button opens a new screen where you will find the more finer points of setting up your overclock and fan profiles. Each GPU can be selected independently although it makes sense that you would set both cores to the same level.

The monitoring section allows you to set an alarms should your GPU reach a preset threshold or your fan fall below a designated RPM.

The SmartDoctor allows the user to determine the coustic and cooling level of the graphics card via 3 options: Manual Mode, SmartCooling or Auto setting.

Hyperdrive is a feature that should be put to good use with a GPU as powerful as this. It works by increasing the clockspeed when the GPU detects you are running a 3D application and slows the card down when not under any strain. This coupled with the fan control system should mean that when you are browsing the net you can do so in relative peace but you have the GPU processing power to hand when you fire up your favourite game.

GamerOSD is a utility very similar yet a little less complex than FRAPS. It allows the user to record movies and take screenshots using adjustable HotKeys.

Overdrive gives uses the ability to overclock their graphics card and monitor temperatures and fan speed. Whilst not as thorough as MSI Afterburner, it is still a very useful tool. The only problem is the low upper limit set on the core speed. The new feature, shown above as Power Control Settings, is AMD PowerTune.

AMD PowerTune

Overclocking is nothing without stability and for most enthusiasts; applications such as Furmark, OCCT or MSI Kombustor have been the stress test of choice to truly load graphics cards. However, both AMD and Nvidia have voiced their concerns against the use of such applications due to the number of cards killed as a result of high temperatures and unforgiving load. They believe that stress tests are not representative of gaming loads and should therefore not be used as an indicator for stability.

This is where PowerTune comes in. The basic concept is that it locks the GPU’s thermal design power (TDP) to a pre-determined value such that when it is exceeded, the GPU will try to lower power usage. This is achieved by simply lowering the clock speed when the pre-determined TDP is attained under load. On the HD6950, the PowerTune Maximum Power is set to 200W whilst on the HD6970, it is set to 250W. AMD claim that typical gaming loads would draw 140W using the HD6950 and up to 200W using the HD6970, meaning that in typical scenarios, gamers shouldn’t worry about their cards reaching the maximum TDP and throttling. The main situation where it PowerTune would kick in is under heavy loads from programs such as the stress test applications mentioned above.

Overclocking presents another scenario where throttling might occur. Not surprisingly, overclocking will increase the power draw both in game and in stress tests closer to 200W/250W. This means that the card will be more susceptible to throttling as they exceed the PowerTune maximum TDP. AMD realise that PowerTune may not appeal overclockers but rather than giving them the option to disable the feature, they provide power control settings in Overdrive. Raising the limit to 20% sets the new maximum TDP to 240W on the HD6950 and 300W on the HD6970, still within ATX specifications. This gives overclockers additional headroom before throttling occurs. It also means that at stock clocks, the chance of getting reduced performance is much less. Conversely, to increase power efficiency, the power control settings can be reduced by 20%, making it ideal in situations where higher clock speeds are not needed.

In some ways, the system is akin to Turbo mode on both AMD and Intel CPUs. In the latter case, if power draw is within the TDP, the CPUs will have their speed boosted. Therefore, under light load, the CPUs will operate faster and simply clock to default speeds when the TDP is reached. In the HD69XX’s case, the core works at its default clocks and throttles when the TDP is reached. Nvidia have employed a similar feature on their GTX580/570 for the same reasons as AMD.

Throughout the benchmarks, the PowerTune limit was set at 20% to ensure overclocking headroom. However, at stock speeds, there was no noticeable performance difference between the 0 and 20% settings.

Overclocking & Temperature Analysis

Overclocking

When reviewing a graphics card we normally run the benchmarks in a stock and a user overclocked state. This time however ,we will be assessing the increases that the AUSUM switch affords the end user. Of course, Vortez wouldn’t be Vortez if we didn’t push the envelope a little further so without further a do, let’s see what we achieved:

Stock settings

At stock, the ASUS HD6990 weighs in at a conservative 830MHz on the core and 1250MHz (5000MHz effective) for the memory.

AUSUM Overclock

By enabling the second BIOS option with the hardware switch, the AUSUM overclock increased the stock values by 50Mhz on the core and 125MHz on the memory (500Mhz effective) making the overall clockspeeds 880/5500MHz.

To overclock further than stock AUSUM settings we used the AMD Catalyst ‘Overdrive’ utility:

Maximum Overclock achieved

The maximum we could get the ASUS HD6990 was an amazing 1010MHz. At this setting however there was a very high degree of instability resulting in lockups throughout most of our benchmarks even with the fan running at a maximum, ear drum bursting 100%. We did however manage to pass a single run of Unigine Heaven 2.5 but this overclock was far from stable so we reduced the overclock down to a much more reasonable level. This overclock was then tested and proof benched using a one hour burn-in stress of FurMark and multiple loops of 3DMark2011.

Benchmark Overclock

A lot lower than the suicide shot posted granted but it’s still a damn good overclock nevertheless. It is rock solid and like all the overclocks used throughout all of our reviews, one which we would be happy to run everyday in our own systems were it not for the noise which is discussed later in the review.

Temperature

To measure the temperature of the card we first measure the ambient temperature. Our review station resides in an air conditioned room with the temperature set to a comfortable 23c.

Under idle the card sits at around the 43c mark which is very good considering the cooling is stock and the fan is only running at 30%. Things change though when we placed the GPU under extreme load using the FurMark utility. The card increased to a toasty 74c which however is still very much under control.

Enabling the AUSUM switch meant the temps rose again slightly across the board but thankfully, the temps were never nearing the point of no return, maxing out at a balmy 80c.

With our maximum stable overclock dialed in, the core temperature began to touch on uncomfortable levels, peaking at 88c, however the fan was noticeably much, much louder, working a lot harder to dissipate the heat. At this clockspeed, the fan noise was something I would be not be content to endure while gaming so while the extra overclocking headroom was very welcome, the fan noise was most certainly not! It is worth pointing out that the backplate gets extremely hot too and while there is no sensor for this to accurately report temps, it was certainly too hot to touch for any length of time.

Acoustics & Power Consumption

Acoustics

Often overlooked when purchasing a graphics card is the noise that it emits. We all hear (no pun intended) of graphics cards that run like a jet engine which can have a detrimental effect on a gaming session, regardless of the FPS it churns out. It is therefore extremely important that a graphics card should operate as quietly as possible.

To test for this we will be using a sound meter and microphone setup which will be placed 20cm away from the GPU. The test will take place in a quiet (not sound proof) room with the results for the GPU fan at idle and load settings. FurMark will be the utility of choice as it will give you a worst case scenario.

Results

When idle, the GPU fan does not make much noise with only a very slight ‘whooshing’ of air being noticed every so often however it is certainly not intrusive by any means, topping out at 57dB. This is actually a very good result when you consider the IceQ cooler from HIS gives us the same reading, despite the fan only having to keep one core under control. Increasing the load on the card however meant the fan speed also increased resulting in quite a lot of noise. With 5 minutes of FurMark Burn-In test completed we measured an output of 76Db. At this level you can certainly hear the card and what’s more, if you prefer playing with a speaker setup, it would interfere with your gaming experience.

For giggles, I also set the cards fan to run at 100%. Like a jet preparing for take-off, the fan slowly picked up momentum until it peaked at 90dB. The noise is almost the same as a hair dryer, not something you want next to your head while listening out for footsteps in a game. Fearing for my hearing and not wanting to trigger car alarms in the office car park, I set the fan back to auto and the noise slowly subsided.

Power Consumption

For this test, we will be using a wall meter with the test setup plugged in minus the Monitor. Readings were taken at both stock and overclocked conditions each having readings also taken in idle and 100% load (Furmark).

Results

Despite consuming more power than the much less hungry GTX560, the HIS HD6970 IceQ Turbo was still surprisingly frugal, even when placed under load. Our test setup is certainly not low end by any stretch of the imagination so with HIS recommending a 550w PSU as a minimum, I believe we have shown that should you not heavily overclock your setup you could perhaps get away with a PSU slightly less powerful and still have a little headroom.

Let’s move on with the review and get to the bread and butter; the synthetic and gaming benchmarks…

Crysis Warhead

Following the success of Crysis, the stand alone expansion “Warhead” was hotly anticipated to bring more game play, more weapons, improved visuals whilst maintaining better performance, the latter being what gamers wanted most. After all how many people upgraded their rigs just to play this game… In the game, you play as the upbeat Brit Sergeant “Psycho” Sykes, chasing down a Korean nuclear warhead. Throw in some ice shooting aliens and we’re bound to have a great game. It sure delivered.

Testing was done using Framebuffer’s Crysis Warhead benchmarking tool. The tests were configured to DirectX 10 at Enthusiast levels. Each test on the Ambush map was looped three times from which the average FPS was recorded.

Far Cry 2

One of the most hyped games of 2008, Far Cry 2 had some big shoes to fill. It was built to be the next best thing since well… Far Cry I suppose. Combining an open-world game play with highly detailed graphics, physics and AI, what more could we possibly want? The game puts us in the body of a malaria inflicted mercenary hunting down the “Jackal” in the heart of Africa, in a bid to stop an on-going conflict between two rival factions. The storyline can be hard to follow sometimes but I’m no game reviewer, so let’s concentrate on the graphics and performance. After all, we all need to know if our hardware will be able to handle the scorching savannah burning at the hands of our flamethrowers.

The bundled benchmarking tool was used on Far Cry 2, configuring the settings to Ultra and DX10. The small ranch level was chosen and each configuration was looped three times from which the average FPS was recorded.

Metro 2033

Based on Novel by the same name, Metro 2033 is a first person shooter with elements of survival horror. As Artyom, you trawl through the mutant infested metro systems of post-apocalyptic Moscow. The game delivers presents a grim ambience that reflects on the overall atmosphere of the underground setting. Metro 2033 uses the setting as a back drop to showcase some of the best visuals of any games out now, making it the ideal benchmark for those looking for the best graphics card.

The bundled benchmarking tool was used on Metro 2033, configuring the settings to Very High and making use of DirectX 11. The frontline scene was looped 3 times for each configuration. The average FPS was recorded at the end.

Alien vs Predator

Spawned from the popular Alien and Predator franchises, Rebellion have collaborated to bring the legendary war to us through the medium of a first-person shooter. The game forces you to hunt, prey and most importantly survive in the swamp colony of Freya’s prospect as a Predator, Alien or Marine. The stunning visuals add to the sense of dread and terror that we have become so accustomed to seeing with the series.

The stand-alone Alien VS Predator benchmark tool was used for testing here. All the settings were set to very high and Tessellation was applied. The average FPS was recorded at the end.

Battlefield: Bad Company 2

Battlefield Bad Company 2 is the new rendition of the widely successful Battlefield series of game. Having more in common with the console release of Bad Company, the sequel hopes to inject the DNA of the timeless Battlefield 2 online experience with the witty action packed single player shooting adventure of the original. As Private Preston Marlowe, your goal as a member of Bad Company is to once again save the world by securing a scalar weapon device.

Fraps was used to test performance. Each test was conducted at the start of the ‘Cold War’ level ensuring that the same actions and paths were taken during the 2 minute sample. All settings were set to the highest available in game with AF set to 16x and HBAO turned on. The average FPS was recorded by FRAPS at the end of each walk through.

DiRT 3

As players race to elevate their global standing, DiRT 3 is back delivering mud, sweat and gears world over: from the intense weather-beaten rally stages of Europe, Africa and the US, to executing performance driving showcases and career challenges where car control is pushed to spectacular limits.

The in-game benchmarking tool was used to test performance. All the display settings were set to the maximum available and DirectX 11 was applied. The average FPS was recorded at the end.

Mafia II

Following the success of Mafia back in 2002, the third person action adventure game is back with a new grittier and darker world. As Vito Scaletta, an aspiring made man, your job is to work through the twist and turns of Mafia lifestyle. The more blood spilt, the more you get in return but the lifestyle was never meant to be an ideal one. Set in the visually stunning Empire City, the wartime references provide the ever present back drop to a rife period in America’s history, in which potential for exploitation becomes Vito’s key focus.

The in-game benchmarking tool was used to test performance. All the display settings were set to the maximum available in-game. PhsyX was only enabled if specified in the charts. The average FPS was recorded at the end.

TessMark 0.2.2

TessMark 0.2.2 is an OpenGL benchmark and tech demo that uses the new hardware tessellation (or GPU tessellation) features exposed by the OpenGL 4 API. Hardware tessellation makes it possible to divide a polygon into smaller ones (according to the tessellation level factor) in order to increase polygons density: the higher the tessellation level, the higher the polygon density. A high tessellation level requires much GPU processing power.

TessMark was run in fullscreen, benchmark mode using map set 1 and configured to use OpenGL 4.

3DMark 11 & Unigine Heaven 2.5

3DMark 11 is the latest version of the world’s most popular benchmark. Designed to measure your PC’s gaming performance 3DMark 11 makes extensive use of all the new features in DirectX 11 including tessellation, compute shaders and multi-threading.

Unigine Heaven 2.5

Heaven Benchmark is a DirectX 11 GPU benchmark based on advanced Unigine™ engine from Unigine Corp. It reveals the enchanting magic of floating islands with a tiny village hidden in the cloudy skies. Interactive mode provides emerging experience of exploring the intricate world of steampunk.

Conclusion

Amazing is not a word I would use to describe the performance of this card. Ground breaking? Nope, that doesn’t quite fit the bill either. Perhaps the only word to describe the performance of the ASUS HD6990 in the English language is phenomenal. I would add some expletives to this adjective but for the younger audience who may be reading! The flagship graphics card cut through the majority of tests within our very demanding benchmark suite like a knife through butter. This was in stock format of course. With a flick of the AUSUM switch, performance improved again and should you be crazy enough to want even more speed then the HD6990 will happily oblige. We have shown today that two cores are certainly better than one and while the performance is not precisely double that of a single core solution, frames per second numbers were very close. I loved by 3870×2 but felt let down by drivers and spurious support in the past which was found wanting for the latest and greatest games. Micro-stuttering is another cross dual core cards have to bear. I am however, happy to report I found no such issues with the HD6990. In short the card performs to the extreme levels you would expect for such a price and herein lies the crux of the HD6990.

£500 will buy you a mid range pc, a stag weekend in Amsterdam or indeed a budget family holiday. Justifying the same amount of cash for a PC component will take some very serious persuasion to your better half. Whichever way you look at it, in today’s financial climate, £500 is a lot of money to spend on a graphics card. If however you are lucky enough to have £500 spare, have the saving discipline of a miser or indeed you are on first name terms with your bank manager then this graphics card is certainly worth a punt.

While I feel I may be condescending here, it is worth pointing out again that you will need a good quality 700w+ power supply unit to run this card. Our test system showed that under extreme overclocks and extreme strain the whole system drew a little over 600W from the wall. This figure is however conservative and is an average reading. It does not take into account spikes of power draw which can bring an abrupt halt to your gaming needs when your PSU OV protection kicks in. You will also need to bear in mind that our test system does not have additional hard drives to power, cold cathodes nor other USB devices other than a keyboard and mouse so if your setup is one which has lots of peripheral devices, a hard drive whore or indeed one which also has lots of fans and watercooling, you will certainly want to consider investing in more power than the recommended 700w, especially if you dabble in the dark art of overclocking.

My one disappointment and perhaps the only reason I would advise against buying this GPU (other than the price of course) is the high levels of noise the card makes. Most high powered graphics cards these days will make a racket when they are worked to extreme levels but the reference cooled ASUS HD6990 takes fan noise to a whole new level. At stock settings it is bearable, just. Crank up the settings and the additional heatdump has to be compensated by a fan that runs at higher and higher rpm’s. As such, the smooth, flawless, graphical gaming experience you witness on-screen is infringed by the din your PC is making. If like me, you prefer to use a headset with the volume wound up to the maximum then this is not an issue. If however you like to envelope yourself in a Dolby II 7.1 surround sound setup then you may wish to pause before getting out the plastic as a quiet card this is certainly not. Were I of that audio persuasion, I can honestly say that the noise would become very tiresome after a short while.

The ASUS HD6990 is not a mainstream graphics card. It is not built for the masses. It is a show piece of technology, a flagship model demonstrating sheer power over any other consideration be it price, power consumption or acoustics. For that it has to be applauded as it is mission successful for AMD. They have created a card that will be on every hardware enthusiasts dream GPU shoping list, the very same people who along with this card put performance above anything else. Couple this phenomenal display of technological prowess with the exceptional support ASUS now provide and the overall package becomes even more appealing. Had the price been more comfortable and the noise been acceptable then this card would have won our coveted Gold award. As such, the ASUS HD6990 will have to settle for silver, not because it is second best, it clearly isn’t but should a custom cooled version become available, perhaps at a relaxed price point, then that card would be more deserving of our premier award.

Now, where did I put my credit card…

Pros
+ Class leading performance
+ Brilliant CrossFire scaling
+ Excellent tessellation and AA performance
+ Out of the box Eyefinity support
+ Large framebuffer
+ Well packaged
+ Aesthetics
+ Good overclocking headroom and voltage tweaking software

Cons
– Size
– Noise
– Cost