AMD Radeon HD 7870 GHz Edition & Radeon HD 7850 Review: Rounding Out Southern Islands
by Ryan Smith on March 5, 2012 12:01 AM ESTCompute Performance
Moving on from our look at gaming performance, we have our customary look at compute performance. With GCN AMD significantly overhauled their architecture in order to improve compute performance, as their long-run initiatives rely on GPU compute performance becoming far more important than it is today.
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.
The Civ V compute shader benchmark once again shows off just how much the compute shader performance of the 7800 series has improved relative to the 6900 series, with both 7800 cards coming in well, well ahead of any previous generation AMD cards. Compared to NVIDIA’s lineup the 7800 series does fairly well for itself too, although not quite as well as the commanding lead the 7900 series took.
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.
SmallLuxGPU continues to showcase the 7800 series’ improvements over past AMD architectures, and while it’s not the same kind of massive leap we saw with CivV, it’s still enough to bring the 7850 up to near the performance of the 6970, and pushing the 7870 well beyond that. The only real competition here for AMD is AMD.
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.
On the one hand, the 7870 gets quite close to the 7950 here in our AESEncryptDecrypt benchmark, in spite of the latter’s higher number of shaders. On the other hand, it’s still not enough to dethrone the GTX 570; the only NVIDIA cards the 7800 series can beat start at the GTX 560 Ti.
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.
In our final compute test the 7800 series once again makes a run at the top, with both cards rising past the GTX 570, although they can’t quite match the GTX 580. In an interesting turn of events the 7870 ends up being some 6% faster than the 7950, in spite of the fact that in a compute benchmark the 7950 should have a solid lead. This just goes to show that core clockspeeds do matter, and that adding more shaders alone can’t conquer all benchmarks.
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arjuna1 - Monday, March 5, 2012 - link
Metro 2033 (the highest settings bench)Radeon 7950 33fps
Radeon 6970 27.5fps
Radeon 6870 32fps (the second highest bench)
Weee!!! $400+ for 5.5fps more.
Not sure about you, but to me, spending that kind of cash for an imperceptible increase in performance is having no sense of money's worth.
This generation of cards can safely be skipped until the 8xxx/7xx series from both AMD and NVIDIA.
Death666Angel - Tuesday, March 6, 2012 - link
Picking up one specific benchmark to underline your point. Great reasoning skills, you should join a debate team! Also, that 5.5fps is still 20%, with the good track record of overclockability, it can reach as much as 40%. But you stick to your point.arjuna1 - Tuesday, March 6, 2012 - link
What? were you expecting me to post a powerpoint presentation for just for you??The numbers are there, look at them if you want, but hey, be stuck in your point, only a frustrated basement geek can think in way to justify spending $400 +/- for less than 50% increase in performance.
Be careful of not falling of that horse, seems pretty high.
sseemaku - Tuesday, March 6, 2012 - link
Please check the avg frame rate improvements, not some specific results. But everyone agrees that 7xxx cards are a bit overpriced and that's because they don't have competition right now. If you worry about power consumption, buy these cards now. Or more interested in price/performance, wait till Kepler is released.arjuna1 - Tuesday, March 6, 2012 - link
I can agree with that, after Kepler is release prices will go down and maybe then the 7xxx series will increase in the perceived value.CeriseCogburn - Thursday, March 8, 2012 - link
If there's no competition then they aren't overpriced because they cannot be touched by anything, hence making their price absolutely correct !!!I call that "reality".
If Kepler blows their doors off, their price will fall. That's reality too.
It's time for all the amd is cheaper crud to go the way of the dinosaur.
Recently a 460 was an unbeatable value. Then a 560ti was as unbeatable value. Currently a 6870 is an unbeatable value.
These things happen, and a deal is not the general aspect of the video card prices, which generally speaking wind up right where they should be.
The deal is the exception to the usual rule across the board, and "the deal" as in "big price drop" is usually just one card here or there for a short period of time.
CeriseCogburn - Thursday, March 8, 2012 - link
Radeon cards have been coming out at $700 and $600 and $500+ for a long time man - even with competition.I don't know what planet you people come from when the constant repetition of "it sounds good" becomes an absolute meme and ongoing restated theme but in no way reflects even a tiny kernel of truth as far as reality goes.
CeriseCogburn - Friday, March 9, 2012 - link
Yes dagamer34, Ryan praises amd for drying up their 6000 series channel with such precision. Then we get this praise - the perfect price structure by AMD, and "it's conservative pricing" according to the author even though it's $40 and $30 higher than it's Nvidia counterpart..." With AMD targeting the ~$320 570 and ~$210 560 Ti and given their conservative pricing on the rest of Southern Islands, it should come as no surprise that the 7800 series is priced equally conservatively. The 7870 will have an MSRP of $350, while the 7850 will have an MSRP of $250. With the 7800 series completing the launch of Southern Islands, this gives AMD a consistent price structure for the entire family: $550, $450, $350, $250, $159, and $109."
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I see. So more expensive is conservative, and the 6 AMD price figures are perfect and consistent...
I am so sick of it...
Falkenad2 - Monday, March 5, 2012 - link
Thus far, AMD's first foray into 28nm graphics has been unimpressive. From a price/performance standpoint, the 7000 series has not given the usual incentives for upgrading that is regularly associated with the move to a new node. I hope a strong competitor from nVidia is on the way, as that would bode well for consumers such as ourselves. As it stands, the 7000 series lacks value except at the very high end, where price/performance is of little concern.Kaboose - Monday, March 5, 2012 - link
Price vs. performance is not the only factor, some people are concerned with power draw as well. Others are interested in temps, and noise. The price could use some work (come on Nvidia) but besides that the 7xxx series has been fairly impressive in regards to overclocking, power, temp, and noise.