AMD's Radeon HD 6990: The New Single Card King
by Ryan Smith on March 8, 2011 12:01 AM EST- Posted in
- AMD
- Radeon HD 6990
- GPUs
Compute Performance
Moving on from our look at gaming performance, we have our customary look at compute performance. With AMD’s architectural changes from the 5000 series to the 6000 series, focusing particularly on compute performance, this can help define the 6990 compared to the 5970. However at the same time, neither benchmark here benefits from the dual-GPU design of the 6990 very much.
Our first compute benchmark comes from Civilization V, which uses DirectCompute to decompress textures on the fly. Civ V includes a sub-benchmark that exclusively tests the speed of their texture decompression algorithm by repeatedly decompressing the textures required for one of the game’s leader scenes.
New as of Catalyst 11.4, AMD’s performance in our Civilization V DirectCompute benchmark now scales with CrossFire at least marginally. This leads to the 6990 leaping ahead of the 6970, however the Cayman architecture/compiler still looks to be sub-optimal for this test. The 5970 has a 10% lead even with its core clock disadvantage. This also lets NVIDIA and their Fermi architecture establish a solid lead over the 6990, even without the benefit of SLI scaling.
Our second GPU compute benchmark is SmallLuxGPU, the GPU ray tracing branch of the open source LuxRender renderer. While it’s still in beta, SmallLuxGPU recently hit a milestone by implementing a complete ray tracing engine in OpenCL, allowing them to fully offload the process to the GPU. It’s this ray tracing engine we’re testing.
There’s no CrossFire scaling to speak of in SmallLuxGPU, so this test is all about the performance of GPU1, and its shader/compute performance at that. At default clocks this leads to the 6990 slightly trailing the 6970, while overclocked this leads to perfect parity with it. Unfortunately for AMD this is a test where NVIDIA’s focus on compute performance has really paid off; coupled with the lack of CF scaling and even a $240 GTX 560 Ti can edge out the $700 6990.
Ultimately the take-away from this is that for most desktop GPU computing workloads, the benefit of multiple GPU cores is still unrealized. As a result the 6990 shines as a gaming card, but is out of its element as a GPU computing card unless you have an embarrassingly parallel task to feed it.
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Figaro56 - Tuesday, March 8, 2011 - link
Just be prepared to upgrade your GPU every year. If you think they are going to stop leap frogging performance you are not being realistic.san1s - Tuesday, March 8, 2011 - link
"AMD even went so far as to suggest that reviewers not directly disassemble their 6990"The next picture: The card disassembled
haha
Ryan Smith - Tuesday, March 8, 2011 - link
To AMD's credit, they were good sports offered to take any pictures we needed. So all of those disassembled shots came from them. They were really adamant about it being a bad idea to take these things apart if you intended to use them in the future.strikeback03 - Tuesday, March 8, 2011 - link
I was looking for a comment on whether you did all your testing before disassembling or whether you got some of their super paste to reassemble.7Enigma - Tuesday, March 8, 2011 - link
My problem with the shot is the poor application of thermal paste from the picture. In a card of this magnitude having a perfect coating of thermal compound is critical. And knowing marketing if that is the shot they SHOW, how good do you really think the application is on one purchased in retail channels?iwod - Tuesday, March 8, 2011 - link
I haven't been following CrossFire / SLI or these Single Card Dual GPU closely. ( Which to me are the same as two card anyway )Do they still need drivers to have a specific profile of the game to take advantage? I.e an Unknown Game to the Drivers will gain 0 benefits from the 2nd GPU?
If that is so, then they are not even worth a look.
Figaro56 - Tuesday, March 8, 2011 - link
Most of the big games support SLI and CrossfireX today. For example, I play Battlefield BC2 myself and using 2 video cards blows the doors of a single card and is well worth the investment, especially if you have a 2560x1600 resolution monitor like I do. For 2 ATI cards in Crossfire you install a separate crossfire profiles pack in addition to the catalyst drivers. The profiles pack supports all the game crossfire optimization. The AI mode in the catalyst drivers exploits the game profile pack setting for crossfire so you want that enabled.A dual GPU HD 6990 is essentially crossfire on a single card, but for some reason it doesn't perform as well as dual single GPU cards in crossfire. Go figure.
If you play old games that don't support SLI or Crossfire then YES there is 0 gain. If you have not tried any of the new games what are you waiting for? It doesn't suck you know?!
cactusdog - Tuesday, March 8, 2011 - link
I agree, unless you have eyefinity and one slot, paying a premium for heat and noise doesnt make sense. For most people with 1 screen a 6970 or 580 is more than enough.Samus - Tuesday, March 8, 2011 - link
i'd be shocked if they sold even one of these without it being returned at some point. the noise levels are astonishing. at full blast the thing doesn't even meet federal vehicle emissions noise regulations without being classified as a motorcycle!MadAd - Tuesday, March 8, 2011 - link
8%? where do we buy tubes of this phase change material? do they sell it like arctic silver?