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NVIDIA vs AMD: GPGPU performance

Asked 2011-01-09T08:27:54.893
109

I'd like to hear from people with experience of coding for both. Myself, I only have experience with NVIDIA.

NVIDIA CUDA seems to be a lot more popular than the competition. (Just counting question tags on this forum, 'cuda' outperforms 'opencl' 3:1, and 'nvidia' outperforms 'ati' 15:1, and there's no tag for 'ati-stream' at all).

On the other hand, according to Wikipedia, ATI/AMD cards should have a lot more potential, especially per dollar. The fastest NVIDIA card on the market as of today, GeForce 580 ($500), is rated at 1.6 single-precision TFlops. AMD Radeon 6970 can be had for $370 and it is rated at 2.7 TFlops. The 580 has 512 execution units at 772 MHz. The 6970 has 1536 execution units at 880 MHz.

How realistic is that paper advantage of AMD over NVIDIA, and is it likely to be realized in most GPGPU tasks? What happens with integer tasks?

cuda opencl gpgpu nvidia ati
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2 Answers

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I've done some iterative coding in OpenCL. And the results of running it in NVIDIA and ATI, are pretty much the same. Near the same speed in the same value ($) cards.

In both cases, speeds were ~10x-30x comparing to a CPU.

I didn't test CUDA, but I doubt it could solve my random memory fetch problems magically. Nowadays, CUDA and OpenCL are more or less the same, and I see more future on OpenCL than on CUDA. The main reason is that Intel is launching drivers with OpenCL for their processors. This will be a huge advance in the future (running 16, 32 or 64 threads of OpenCL in CPU is REALLY fast, and really easy to port to GPU).

answered 2011-05-26T23:27:50.143
7

My experience in evaluating OpenCL floating point performance tends to favor NVIDIA cards. I've worked with a couple of floating point benchmarks on NVIDIA cards ranging from the 8600M GT to the GTX 460. NVIDIA cards consistently achieve about half of theoretical single-precisino peak on these benchmarks.
The ATI cards I have worked with rarely achieve better than one third of single-precision peak. Note that my experience with ATI is skewed; I've only been able to work with one 5000 series card. My experience is mostly with HD 4000 series cards, which were never well supported. Support for the HD 5000 series cards is much better.

answered 2011-01-09T18:46:50.003

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