AMD Radeon HD 7950 Review Feat. Sapphire & XFX: Sewing Up The High-End Market
by Ryan Smith on January 31, 2012 9:02 AM ESTCompute Performance
Moving on from our look at gaming performance, we have our customary look at compute performance. Since compute performance is by definition shader bound, the 7950 is at a bit of a disadvantage here compared to gaming performance. Whereas ROP performance scales with the core clock, shader performance is hit by both the reduction in the core clock and the disabled CU array.
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. Note that this is a DX11 DirectCompute benchmark.
AMD’s greatly improved compute performance continues to shine here, though in the case of Civilization V it’s largely consumed by just closing the previously large gap between the GTX 500 series and the Radeon HD 6000 series. As a result the 7950 falls ever so short of the GTX 580, while the factory overclocked Sapphire and XFX cards give the 7950 enough of a push to come within 5% of the 7970.
Our next benchmark is SmallLuxGPU, the GPU ray tracing branch of the open source LuxRender renderer. We’re now using a development build from the version 2.0 branch, and we’ve moved on to a more complex scene that hopefully will provide a greater challenge to our GPUs.
Under SmallLuxGPU the 7970 enjoyed a large lead over the GTX 580, and this continues with the 7950. Even though the 7950 is well behind the 7970—to the tune of 24%—it’s still 33% ahead of the GTX 580 and the lead only grows from there. Meanwhile the XFX and Sapphire cards can catch up to the 7970 somewhat, but as this is truly a shader-bound test, you can’t make up for the lack of shaders units on the 7950.
For our next benchmark we’re looking at AESEncryptDecrypt, an OpenCL AES encryption routine that AES encrypts/decrypts an 8K x 8K pixel square image file. The results of this benchmark are the average time to encrypt the image over a number of iterations of the AES cypher.
In spite of being a compute benchmark, AESEncryptDecrypt is not particularly sensitive to GPU performance, showcasing the impact that setup times can have. The 7950 trails the 7970 by 10%, and overclocking doesn’t change this much. Unfortunately for AMD NVIDIA is still the leader here, showing that AMD’s compute performance still has room to grow.
Finally, our last benchmark is once again looking at compute shader performance, this time through the Fluid simulation sample in the DirectX SDK. This program simulates the motion and interactions of a 16k particle fluid using a compute shader, with a choice of several different algorithms. In this case we’re using an (O)n^2 nearest neighbor method that is optimized by using shared memory to cache data.
With the compute shader fluid simulation we once again shift back into a compute task that’s much more shader-bound. The 7950 only reaches 80% of the performance of the 7970, once more proving the real impact of losing a CU array. This is still enough to handily surpass the GTX 580 however, with the 7950 taking a 15% lead.
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SlyNine - Tuesday, January 31, 2012 - link
I think it's you that has been sleeping. You're comparing EBay prices for god sakes. We are talking about new releases.The 5870 released 2 1/2 years ago at 379$. It was 2x as fast as the 4870.
When the 4870 released it cost what, 300$ in mid 2008. It was over 2x as fast as the 3870.
How about the amazing 9700pro at around 400$, In some cases being 4X faster then the 4600TI.
This is perhaps a step up from the to the likes of the 2900XT or 5800ultra. But both of those had some rocking competition to deal with. Like the 8800GTX and the 9700pro.
If you think this 30% better performance is worth 580$ then you have no concept of value.
Phate- - Tuesday, January 31, 2012 - link
It took you long enough to notice. Better to go and have this discussion in the comments of the HD6970 review.Galidou - Tuesday, January 31, 2012 - link
Because it's next gen, performs better for the same price and overclocks probably WAY better plus maybe a chance to mod it to 7970? Is that enough?SlyNine - Tuesday, January 31, 2012 - link
Its not better performance for the same price. This time the price has scaled with performance.Normally when a new GPU gen releases its much better performance at the same price as the previous kings release.
Look at the 9700pro, 8800GTX, 5870. Those were great cards for the time. The 7970 is just, Eh. Not bad enough to be considered a 2900XT or a 5800 Ultra. But at least those 2 cards had much better competition.
bhima - Tuesday, January 31, 2012 - link
Actually, AMD's prices for these cards are SO bad, most people will just wait or buy older tech. Hell at least Intel's Sandy Bridge i5-2500K came out at a reasonable $215 which really isn't that high for the performance you get from it... in fact, there is no other CPU at the same price that even comes close, nor was there a CPU last year for the same price that even comes close. Here, AMD is pricing themselves out of the market.mdlam - Tuesday, January 31, 2012 - link
Right, and their egregious pricing mistake is why all their cards are selling out since launch. Because all of AMD's business MBA's and experts are no match for your idea of "a good deal"Maybe you've noticed that things are usually more expensive at launch because of hype, and the fact that you have the fastest card makes pricing irrelevant. Well hell whatever, you didn't even notice that Sandy bridge 2500k opened up at $260-270 dollars at launch, what's the point in taking this further.
Dribble - Tuesday, January 31, 2012 - link
I noticed that when the 5870 and 5850 came out they blew away the competition and were relatively cheap. What was the 5850 price when it came out - about half of the 7950? Yet the performance leap over previous gen for 5850 was much larger then for 7950. That's why everyone is a bit disappointed.gibsnium - Tuesday, January 31, 2012 - link
The 2500k launched that the same price it is today; bought one from newegg at 219$ at launch.
Master_shake_ - Tuesday, January 31, 2012 - link
doesn't anyone else remember when the 8800 ultra was released and Nvidia threw a thousand dollar price tag on it???how short are your memories??
mdlam - Tuesday, January 31, 2012 - link
I remember it can barely run crysis