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What is needed to make a GPU fully fed by CPU?

Comparing their flops/s is enough?

For example, if i could manage to make a very old(pentium-3) CPU with one of Nvidia-Fermi GPU, it would not be able to fed the gpu with data per sec. What is the criteria to fit CPU to GPU exactly when OpenCL or some similar work needed?

Of course RAM and BUS will be chosen in a similar way but how exactly?

Assume each GPU-core will calculate a sqrt and a division and an adding for 100 times for every itearation.

Thanks.

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closed as not constructive by studiohack Sep 15 '12 at 19:10

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2 Answers

up vote 2 down vote accepted

As Lucas Kauffman noted, it depends on your application.

If you need to feed GPU big amount of data from hard drive without any pre/post-processing on CPU, then CPU is nearly irrelevant. If before/after/during processing data on GPU it needs heavily processing on CPU, then CPU might become the limiting factor.

Several rules-of-thumb:

  • Your CPU should have at least N+1 cores, where N is number of GPUs.

  • You should have at least as much RAM as have all your GPUs in sum.

  • Your PCI-Express bus should be the latest version supported by your GPU (note, that on some motherboard with e.g. 2 PCI-Express slots each might function at x16 speed, but when used together, each is limited to x8). After all, PCI-Express is most common bottleneck for GPUs.

  • If you need video output from your box, consider buying some cheap card for this sole purpose. To avoid any complications with drivers, stick to the same vendor as of your number-crunching cards.

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Just use PS3's. Japan used I believe 1000+ for a super computer –  Cole Johnson Sep 15 '12 at 18:02
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There is not one single answer, there are a lot more factors involved as just feeding information will also depend on what the task at hand will be doing.

But just in short, preferably multiple cores with a high clock-rate.

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I just want to fit different pieces as exactly as possible. Would an openCL library of C++ make true decisions when i use opencl-capable CPU + GPU? –  huseyin tugrul buyukisik Sep 15 '12 at 16:56
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