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matnath1
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Folding with GPU and CPU PPD

Wed Apr 04, 2012 12:25 pm

Sorry if this has been covered already but :

I had my 2500K with HD6950 folding 24/7 on the same rig. I recently removed and sold the HD6950 and have left the 2500K folding by itself. It seems that the points per day have not changed and that now there are more points showing up on the 2500K since it is now "dedicated".

Does adding a graphics card for folding diminish the CPU folding numbers? Did I do something wrong?
 
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Re: Folding with GPU and CPU PPD

Wed Apr 04, 2012 12:56 pm

matdem1 wrote:
Does adding a graphics card for folding diminish the CPU folding numbers? Did I do something wrong?


Yes. No. When GPU folding, pretty much one full CPU core/thread is consumed providing data to the GPU and receiving results back from it.

You basically switched from 3 CPU cores and 1 GPU available for folding to 4 CPU cores available for folding. Based on your feedback, it sounds like a single CPU core does more work than your GPU did.
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Re: Folding with GPU and CPU PPD

Wed Apr 04, 2012 1:14 pm

Another part of the points mystery is bonus points. Using only 3 cores, you may have missed a bonus deadline, thereby losing an equal number of bonus points as you gained from the GPU folding.

If you browse around the FAH forums, hardly anyone uses AMD for GPU folding. Apparently Nvidia's drivers don't occupy an entire thread, and so your net gain on points is higher.

The other option is putting an AMD card in an older, slower machine as a dedicated GPU folder - it seems like it will take up a full core no matter how fast the CPU.
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Re: Folding with GPU and CPU PPD

Wed Apr 04, 2012 4:40 pm

AMD's 6xxx and before series are not known to do Folding-type GPGPU (if you code to their own SDK you can get decent results, but not what Stanford is using) very well compared to Nvidia. Otherwise, the ppd lost in GPU folding would be significant enough that an extra core of CPU Folding would not overcome.
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