Radeon HD 6990 ladies and gentlemen is AMD's latest ATI Radeon HD dual-GPU based graphics card. And for now it will be the fastest 'single' graphics card available on the planet. The performance numbers you will see are anything short from astonishing, breathtaking stuff for a wicked product.
For many weeks now the Radeon HD 6990 has been a product of much discussion. Nobody really could confirm what GPUs would be used, how much graphics memory it would get and so on. Well, rest assured. AMD stuck two Cayman XT GPUs (R6970) onto the PCB and allows them to be clock at R6970 speeds as well, in fact you'll get options in clock-frequencies and TDP with the help of a small micro-switch seated on the card, which leads to 2 vBIOS, one with more acceptable TDPs and the other enabling a higher clock frequency mode. Now I've stated it, Cayman XT GPUs, that means the full shader processor count inside that GPU is available, that sums up towards 3072 shader processors (!)
Memory wise, AMD decided not to skimp here either, the Radeon HD 6990 is a card that will be perfectly suited for Eyefinity solutions, say 3 to 5 monitors PER Radeon HD 6990. In such setup it's wise to have a little more memory per GPU, especially with stuff like high anti-aliasing levels in mind. As such the Radeon HD 6990 comes with a flabbergasting 4 GB of graphics memory, that's two GB per GPU.
All in all, we'll have a lot to talk about today, we'll have a quick chat about verbs like Barts, Cayman and Antilles, then we'll describe the architecture a bit better, we'll have a close look at the products with the help of a photo-gallery ... and well that's all followed by power consumptions, heat levels and performance measurements of course.
Next page please.
An Islands Euphemism & Family Tree
AMD/ATIs naming scheme has not been rather clear lately. Next to a recent change in the Radeon HD 6000 numbering scheme, you'll have heard codenames flying around as well. Next to that AMD silently eliminated the ATI branding, which in fact has now become AMD.
Let's first dig our teeth in that and explain what is going on.
A bit of confusion out there on the street, is that people call the one released today "Antilles" -- which in fact are two "Cayman" graphics processors slapped onto one graphics card. As you might remember in the past ATI (now AMD) assigned code numbers to the GPU used on these graphics cards AKA RV770 or something. Though we are quite confident that the design team still uses that numbering scheme, AMD marketing however wanted to give it a little more TLC and as such each GPU family has a codename, and each GPU deriving from that family has a codename as well.
The previous generation GPUs were named after Evergreen trees which was the family codename; products deriving from that range known as Cypress, Juniper, Redwood and Cedar.
For the Radeon HD 6000 series generation the products are codenamed after islands in the Caribbean, in this case Northern Islands depending on how you look at geographical location, of course.
When we subdivide the Northern Islands groups we get small segments of islands, each GPU range is named after an island for all new Radeon HD 6000 series products, ready? Here they are... Barts, Cayman, Blackcomb, Antilles and Whistler.
When the Radeon 6850/6870 was released in October 2010, the GPUs empowering them carried codename Barts. Bart is named after Saint Barthélemy island and will be the performance/upper-mid segment GPU series. But that still leaves Cayman, Blackcomb, Antilles and Whistler.
Today's high-end products are based on a GPU called "Cayman" (after the Cayman Islands) which is the high-end product in the AMD Radeon HD 6900 series, and that's a change as well, as previously the 5800 series, was the most high-end.
And while we're still on the island rollercoaster , today we test "Antilles", named after the Antilles Islands of course. Antilles is a group of islands, get it .. group ? as in multiple. As such Antilles is a dual-GPU graphics card that makes use of two Cayman GPUs, positioned in the Radeon HD 6900 series of product, carrying the consumer name Radeon HD 6990.
So in a nutshell, Antilles is based on two Cayman GPUs = Radeon HD 6990. Let's move onwards to the actual product. First a word or two on the Cayman GPU.
An Architecture Change
Last year's released cards in the 6800 "Barts" series were the 6850 and 6870. These cards merely received a small architectural optimization/tweak over the last generation architecture, Cypress. With the Antilles/Cayman products, things have changed a little bit as the fundamental section of the GPU, the Shader processor setup underwent a significant change, and we are still debating whether or not it was a good one.
AMD moved from a VLIW5 (also knows as VEC5) towards a VLIW4 SIMD shader processors setup. We are not going to discuss the VLIW4 thread processor setup in much detail but basically what this means is that AMD went from a VLIW5 configuration, that used four simple SIMD units and one complex t-unit (transcendental unit) in order to build a stream processing unit, to a VLIW4 configuration that uses four stream units which feature equal capabilities, two of them being assigned with special functions.
AMD however claims this change will bring them 10% more performance over the previous thread processor setup, better scheduling and register management. We think it was merely a design change to save on the number of transistors which you can re-use to add more shader processors on the processor die.
Next to this rather significant change, there are more changes to be found on the graphics card. It has upgraded render back ends (ROPS) with a redesigned Z-Stencil and ROP unit architecture consisting of 128 Z/Stencil ROPs, and 32 color ROPs, up to 2 times faster in 16-bit integer operations and two to four times faster in 32-bit floating point operations which will have you in AA performance, much faster GDDR5 memory, and we also spot a series of improved compute features that will help out in performance in that segment.
One other detail that you might find interesting is that when you look at the block diagram, you'll notice that the GPU pretty much looks like a dual-core processor. AMD calls this dual graphics engines. Anyway, have a peek at the block diagrams if at all interested.
Alright, some more generic information to grasp. Each Cayman GPU itself is based on a 40nm fabrication process and harbors a blistering 2.64 Billion transistors. The graphics engine can have up-to 24 shader clusters, with each engine holding 64 shader processors. Do the reverse math and you'll quickly learn that the most high-end GPU will count 1536 shader processors. A bit of an unusual number and we just wonder if there isn't more to be found of them inside that die really.
The Cayman chip has up-to 96 Texture Units and can produce 2.7 TFLOPs of single precision performance.
Memory wise AMD of course stuck to it's fine working GDDR5 setup, and yes it is still based on a 256-bit memory bus.
So what about the R6990 ?
So with this knowledge in mind we can now look into the specifications or the R6990 a little more in-depth, next page please.
The Specifications
So then, it is based on two Cayman GPUs, now we can describe the product very easily. Take a Radeon 6970 and multiply everything by two. And that is roughly the R6990 in a nutshell, features and specification wise, yet now it's one card.
Now before I show you the final specifications of the Radeon HD 6990, you need to understand that the card has two modes, normal and unlocked.
The AMD Radeon HD 6990 graphics card features dual-BIOS capabilities. This feature is controlled by an “Unlocking Switch” sitting closely next to the CrossFireX connector on your board. The switch toggles between the factory-supported Performance BIOS of 375W TDP (BIOS1), and a more extreme Performance BIOS (BIOS2) that unlocks higher clock speeds and up to 450W TDP of performance.
For end users to enable this higher performance BIOS, they will have to remove a label covering the dual BIOS switch and set the BIOS switch to the desired position outlined below:
- Position 1 — 450W Extreme Performance BIOS (BIOS2).
- Position 2 — (default shipping position) — 375W factory-supported Performance BIOS (BIOS1).
Let's place that in a table:
Radeon HD 6950
Radeon 6970
Radeon 6990
Radeon 6990 Unlocked
Fab Process
40nm
40nm
40nm
40nm
Die Size
389 mm2
389 mm2
389 mm2 x2
389 mm2 x2
Transistors
2.64 Billion
2.64 Billion
5.28 Billion
5.28 Billion
Core Clock / MHz
800
880
830
880
Memory Clock / MHz
5000
5500
5000
5000
Memory Bandwith
160 GBps
176 GBPs
320 GB/s
320 GB/s
Memory type
GDDR5
GDDR5
GDDR5
GDDR5
Shader processors
1408
1536
3072
3072
Compute performance
2.25 TFLOPS
2.7 TFLOPS
5.10 TFLOPS
5.40 TFLOPS
Color ROPs
32
32
64
64
z/Stencil ROPs
128
128
256
256
TDP Gaming
140 W
190 W
350 W
415 W
Idle power
20 W
20 W
37 W
37 W
The Radeon HD 6990 comes armed with an astonishing 3072 shader processors, thus 48 SIMD based shader clusters, split up in a twofold engine per GPU. The domain and shader clock is locked in at 830 or 880 MHz. The card comes paired with 4 GB of memory clocked at (effective) 5000 MHz (2GB per GPU). The TDP of this product is 350W in default mode, and in unlocked mode the card can consume 415W with a hefty game. There's room left for overclocking in the unlocked design though, you may take the card up-to roughly 450W.
Now, since we have all this knowledge let's just compare this product with some others. Let's have a quick comparative overview of some of the specifications representing a certain scope of other performance parts, you'll notice that the differences are just HUGE, I've inserted the 'default' performance mode in there, not the unlocked one :
Specifications
Radeon HD 5770
Radeon HD 5850
Radeon HD 6850
Radeon HD 6870
Radeon HD 6950
Radeon HD 6970
Radeon HD 6990
GPU
Juniper XT
Cypress Pro
Barts Pro
Barts XT
Cayman Pro
Cayman XT
Cayman XT
Manufact. tech.
40nm
40 nm
40nm
40nm
40nm
40nm
40nm
GPU frequency
850 MHz
725 MHz
775 MHz
900 MHz
800 MHz
880 MHz
830 MHz
Stream processors
800
1440
960
1120
1408
1536
3072
Memory Datarate
4800 MHz
4000 MHz
4000 MHz
4200 MHz
5000 MHz
5500 MHz
5000 MHz
Memory bus
128-bit
256-bit
256-bit
256-bit
256-bit
256-bit
256-bit x2
Memory buffer
1 GB GDDR5
1 GB GDDR5
1 GB GDDR5
1 GB GDDR5
2 GB GDDR5
2 GB GDDR5
4 GB GDDR5
Power consumption
108W
151W
127W
150W
150W
190W
350W
Idle Power
-
-
19W
19W
20W
20W
37W
Impressive stuff huh ? The card of course is an up-to-date DX11 class product with a couple of new features. Features wise, the graphics cards will be very similar to the last generation products and is merely an advanced, updated model. However some features like one DVI and four DisplayPort 1.2 monitor connectors are present for a full Eyefinity experience up-to five cards with just one R6990.
Now before you get concerned about the four DP connectors, the card will ship with 3 adapters to enable Eyefinity gaming out of the box for all users. The product will ship with:
- 1x mini DisplayPort to passive single-link DVI adapter
- 1x mini DisplayPort to active single-link DVI adapter
- 1x mini DisplayPort to passive HDMI adapter
The adapter configuration will enable 3x1 gaming out of the box with DVI panels but with additional display adapters or Display Port displays you will be able to drive up to 5 displays in portrait Eyefinity (5x1 Portrait mode) for the rather grand gaming experience.
Power Management - AMD PowerTune
AMD PowerTune is a new technology that opens up a new direction for maximum performance versus TDP. Pretty much AMD can now limit the maximum TDP applied to a card.
AMD can regulate the TDP with the help of active monitoring. Basically you can lower TDP, have it at normal, or increase the thermal headroom of the graphics cards though the Catalyst drivers. The new feature allows the GPU to be designed with higher engine clock speeds which can be applied on the broad set of applications that have thermal headroom.
So at default it will try and keep your power consumption and TDP at a pre-defined baseline, say 200 Watt. But you'll also have a margin to increase that TDP to say +20%, or vice versa, when you want to limit your power draw you can lower the power usage by -20% (or anything in-between).
- AMD PowerTune can enable higher performance that is optimized to the thermal limits of the GPU by dynamically adjusting the engine clock during runtime based on an internally calculated GPU power assessment.
- AMD PowerTune technology also deals with applications that would otherwise exceed the GPU’s TDP like OCCT, Furmark or 3DMark's perlin noise tests. It does so by dynamically managing the engine clock speeds based on calculations which determine the proximity of the GPU to its TDP limit.
- AMD PowerTune allows for the GPU to run within its TDP budget at higher nominal clock speeds than otherwise possible.
So a monitoring function on the graphics card can be used to downclock your card when needed. And the flipside of the coin is that it can be directly adjusted by the user using the AMD Catalyst Control Center and used for tweaking and overclocking as you can allow for a more aggressive power containment (and therefore more aggressively limit power and heat) or be used by enthusiasts to relax the enforcement of factory thermal constraints on their AMD Radeon HD 6900 Series Radeon graphics card and squeeze every last bit of performance - at the cost of a much higher TDP of course.
Mind you that if you use ATI Overdrive for tweaking the R6990, you'll need to tweak and apply the setting for each GPU independently.
What's That New Switch?
If you look at the photo below you'll notice a tiny micro-switch next to the Crossfire connector. The R6990 cards have one firmware flashable BIOS and one (non flashable) default BIOS, with the switch you can select BIOS 1 or 2.
AMD initially implemented the feature likely to prevent the RMA rate. They know very well that the enthusiast community often re-flashes their cards, often unsuccessfully after which they enter a very expensive RMA procedure at AMD's cost.
With the R6990 AMD decided to expand that function a little as you'll get control over clock-frequencies and TDP. So the dual-BIOS feature now became an “Unlocking Switch”. The switch toggles between the factory-supported Performance BIOS of 375W TDP (830 MHz - BIOS1), and an Extreme Performance BIOS (880 MHz - BIOS2) which unlocks higher clock speeds and up to 450W TDP of performance. it also applies a slightly higher voltage.
- Position 1 — 450W Extreme Performance BIOS (BIOS2).
- Position 2 — (default shipping position) — 375W factory-supported Performance BIOS (BIOS1).
Video acceleration post-processed by your GPU
The x.264 format is often synonym with Matroska MKV, a media file container which often embeds that x.264 content, a much admired container format for media files. Especially the 1920x1080P movies often have some form of h.264 encoding dropped within the x.264 format. As a result, you'll need a very beefy PC with powerful processor to be able to playback such movies, error free without frames dropping and nasty stutters as PowerDVD or other PureVideo HD supporting software by itself will not support it.
Any popular file-format (XVID/DIVX/MPEG2/MPEG4/h.264/MKV/VC1/AVC) movie can be played on this little piece of software, without the need to install codecs and filters, and where it can, it will DXVA enable the playback. DXVA is short for Direct X Video Acceleration, and as you can tell from those four words alone, it'll try wherever it can to accelerate content over the GPU, offloading the CPU. Which is what we are after.
There's more to this software though:
- A much missed feature with NVIDIA's PureVideo and ATI's UVD is the lack of a very simple function, yet massively important, pixel (image) sharpening.
If you watch a movie on a regular monitor, Purevideo playback is brilliant. But if you display the movie on a larger HD TV, you'll quickly wish you could enable little extra's like sharpening. I remember GeForce series 7 having this native supported from within the Forceware drivers. After GeForce series 8 was released, that feature was stripped away, and to date it has to be the most missed HTPC feature ever.
Media Player Classic has yet another advantage, as not only it tries to enable DXVA where possible through the video processor, it also can utilize the shader processors of your graphics cards and use it to post-process content. A lot of shaders (small pieces of pixel shader code) can be executed within the GPU to enhance the image quality. MCP has this feature built in, you can even select several shaders like image sharpening, de-interlacing, combine them and thus run multiple shaders (enhancement) simultaneously. Fantastic features for high quality content playback.
Here you see MPC HT edition accelerating an x.264 version of a movie @ 1080P. Mind you that the one spike in CPU cycles is me starting up the actual capture software.
The Radeon 6000 series will completely accelerate (DXVA) this movie without any issues. Complex Image sharpening is handled by the shaders processors and we have PC 0-255 Color profile activated over the shaders as well to get nicer black levels. Even if we expand this window to a resolution of 2560x1600 the CPU load will remain low and the graphics card manages that resolution fine.
Resource:
-
Download Media Player Classic HC (free public domain software)
The GPU is doing all the work as you can see, the h.264 content within the x.264 file container is not even a slight bit accelerated over the CPU. Read more about this feature right here in this article.
Final words and conclusion
Aaah, as an actor from the TV series Friends once said in peace and tranquility, Unagi. The Radeon HD 6990 is a very impressive card. And for this conclusion we have a lot to talk about.
So with the very short time we had available to make this article, we hope it was an intersting read.
First off, products like the one shown today are always trivial to recommend and most of all, explain. They are expensive and they perform at a level that hardly anyone requires let alone needs. Still that doesn't change the fact that within it's segment and audience, the most high-end cards are desired by a lot of you. Whether it's just to gain a humongous e-peen, an x-factor product or you simple have a desire for the best gaming performance, it's these people that will purchase the Radeon HD 6990, yeah it is a very impressive card.
For the people that like to setup more than one big monitor and would like to setup a 3+ monitor configuration, well, that's where a product like shown today makes sense of course. See AMD did it right. Initially I was worried that AMD would revert to the 6800 (Barts) series GPUs for this product. But no, they opted the best of the best, and that's the Cayman XT series of GPUs, with the full architecture enabled, paired with a massive 2 GB per GPU (4GB total). I mean seriously, hat's off for that decision.
AMD also knew very well that once you put your most high-end GPUs on one board you'd be bound to stumble into a twofold of issues. The first being power regulation, and the second heat versus noise. Now I can make a long story here about TDP, heat and noise but in the long run ... it really isn't bad at all.
Temperatures hover at roughly 85 Degrees C, that's high but not a major concern. To get that temperature down AMD needed to revert to a huge cooling solution, they opted a dual-radiator design with one fan in the middle. Here again, it's very audible towards noisy ... but not annoying. These two factors you do need to weigh in, this is the most high-end product your money can get you and as such, you will need to compromise on that. One can only wonder if and when liquid cooling blocks will be released for the Radeon HD 6990, as that would make it astonishing alright. But yeah, this needed to be said. TDP wise we already knew that AMD has things well under control. And with 331W to 370W (our measurements) depending on what mode you choose, sure we acknowledge it's a lot to swallow, but again the TDP remains very credible for what you are getting in terms of performance.
Performance wise you will receive a product that oozes and chunks out ridiculous numbers in terms of frame rate. I mean we test at 4xAA / 8xAA and honestly, this card just does not care what you throw at it, it'll eat it alive with feathers and all, then it will spit out the bones and ask for more. Remember though to pair a card like this with an appropriate PC. Even our Core i7 Nehalem based quad core processor overclocked at 3750 MHz still will run into some CPU limitation with the somewhat aging games. By the way, CPU limitations / bottlenecks are not necessarily a bad thing. As long as you pass 60 FPS -- honestly who cares ?
So with that much perf in-house, please do flick open all image quality settings a game offers you. I mean, if I take Battlefield 2 Bad Company, which is massively GPU dependant and enable all and only the very best image quality settings, apply 8xAA and we still get 80 FPS on average in a monitor resolution of 2560x1600 (!), well that just says it all really. That's pure, raw and unadulterated performance.
Size wise we do need to make one remark. Please make sure you have enough space to seat the card, it's 31cm in length, that's 12", also make sure that a card like this receives planty of ventilation inside that chassis. A good in and outwards airflow will help you a lot in managing temperatures and thus noise levels as well.
Driver compatibility wise in terms of multi-GPU support, we did not have extraordinary probs, except for weirdly enough our two oldest titles which seem to revert to one active GPU; Anno 1404 and COD MW2, but even these where running 90+ FPS. AMD has improved on multi-GPU game support by releasing very regular APP (application profiles) downloads. So once a new game is released, you should have it running fairly fast in multi-GPU mode. The last few months we have seen some more complaints about proper multi-GPU game support in our forums though, so we suggest to AMD that they keep up their track record and get multi-GPU game support up-to snuff even better.
That said, I like to close this conclusion. The MSRP price tag of the Radeon HD 6990 will be set at 599 EUR, a huge amount of money for a graphics card alright, but it's 300 EUR per GPU. With the Radeon HD 6970 selling at roughly 339 EUR and with Crossfire in mind, this does save you money and you do get an all-in-one product. With the release of the Radeon HD 6990, AMD brings an extraordinary performing product to the market. With dual-GPUs on one PCB, you always need to compromise a little here and there, but the overall package seems to work out really well. The x-factor is there and the performance is phenomenal when that 2nd GPU kicks in and if you like to go really wild with multiple-monitors then this product is starting to make a whole lot of sense.
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