CPU vs GPU

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CPU vs GPU

Postby dephect.13 » Tue Aug 17, 2010 7:20 am

should i set nvidia control panel to cpu or gpu for physx processing? i think that i understand that there are two seperate clients...one for cpu and one for gpu. do both clients work together on the same session? is there an advantage regardless? should i set up an application specific profile for folding@home on nvidia control panel?


windows 7 - 64bit
2.8 core i7 overclocked to 3.2
12gb corsair ram overclocked tremendously
evga ftw3 motherboard
single 480 superclocked (2nd will be here soon)
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Re: CPU vs GPU

Postby PantherX » Tue Aug 17, 2010 11:41 am

Welcome to the F@H Forum dephect.13,

Regarding the PhysX option, some users prefer to select their GPU or leave it as Auto. Some even disable PhysX. Feel free to experiment with your setup and you can report your finding to us here.

There are F@H Clients that your the GPU (GTX 480) and CPU (i7) so it depends on how much you want to contribute (Brief F@H Clients description).

You can run multiple F@H Clients on a system but they should have their own unique Machine ID and separate folders.

I haven't come across anyone setting up a specific profile for F@H but do make sure that you use the supported/recommended Nvidia Drivers.

When you will be adding your second GPU, F@H will not use SLI (its too slow) so you have to set up another instance of the F@H GPU Client (if you want to contribute with that GPU too). You can read my GPU Guide (link in sig) for more details.

Since you have significantly overclocked your RAM, if the F@H Clients give you an error, you may want to reduce the OC so that they will be F@H Stable.
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Re: CPU vs GPU

Postby dephect.13 » Wed Aug 18, 2010 5:42 am

OK, thank you for your help...it took alot of trial and error and googling but i got the folding happening... microsloth's permissions handling is ...lets just skip that... im merely an intermediate level operator. i dont know how to test and see what gives better results for folding. i just uninstalled the folding client and installed the gpu3 client...works great once you run it as admin. my common sense tells me that optimizing for performance and not image quality is the way to go for faster folding, however im not sure, and i think shaders might be a key to faster folding as well. if someone with some insight could post this for me, that would be great...if someone can tell me how to test for the differences in performance of folding, ill post my findings gladly. i have this feeling like cpu should handle the physx for folding purposes. but im not sure it makes a difference. verticle sync should def be forced off.
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Re: CPU vs GPU

Postby ihaque » Wed Aug 18, 2010 7:43 am

Hi Dephect.13,

I think you're confusing settings that affect graphics performance with those that affect folding performance. Assuming you're talking about the performance of the FAH console GPU client independent of any running games, etc (ie, folding not with a game running), none of the settings you've mentioned should make any difference whatsoever. The GPU client does not make use of PhysX; it uses custom physics code written for the GPU using CUDA. The quality/performance slider and vertical sync options you mentioned are relevant only to graphics rendering and not to general computation that uses the GPU (put technically, they affect rendering of DirectX/OpenGL apps, not the execution of CUDA/OpenCL code). In summary - in the absence of a running game, PhysX, the quality slider, vertical sync, and indeed ANY other graphics-related settings in the driver should make no difference whatsoever, because the GPU client doesn't even use those interfaces.

The one setting you've mentioned that could make a difference is shader clock speed. FAH is generally shader-limited, so faster shader clock speeds generally mean faster folding; many forum users overclock their cards for this very reason. However, our official stance is that we discourage overclocking. From our perspective, it's a risky proposition because the card was not certified to run at that speed, and may silently produce incorrect results (even if it doesn't crash). From the donor's perspective, it increases the heat output of what is already a very power-dense board. Put another way - it takes work to keep those suckers cool even at stock clock speeds, especially with multiple GPUs, and it becomes even harder when overclocked.
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Re: CPU vs GPU

Postby dephect.13 » Wed Aug 18, 2010 7:53 am

So I gather I don't need to turn off unused settings to free up anything if I'm not running something that uses it. Got it. And I think I'm getting the idea that the gui doesn't use these either... I'm rockin the supercloked 480 and the fahcore15 is only tacing the cards gpu @ 90 ppercent.. cpu is shelling out a mere 3 percent. Is it safe to say I should run a seperate client for cpu only? Or are my settings for the client not optimized... I get the feeling from reading these forums that I should be using the console clients and not the sys client.
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Re: CPU vs GPU

Postby bruce » Wed Aug 18, 2010 8:21 am

The choice between a systray client and a console client is strictly personal preference . . . provided the client you want has both choices. Obviously if the systray client hasn't been released yet, you'll only have one choice.

If I had a CPU that was 97% idle, I'd start a uniprocessor client, but I'd make sure it was at a lower priority than the GPU client.
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Re: CPU vs GPU

Postby dephect.13 » Wed Aug 18, 2010 8:29 am

The console client seems to havve more 3rd party support. I think I will take your advice bruce. Thank you to all who posted for a noob donor.
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Re: CPU vs GPU

Postby bruce » Wed Aug 18, 2010 8:53 am

I don't think so. With the exception of the title page in FAHlog, both the systray and the console clients produce exactly the same files, and 3rd party support is based on their being able to parse the files and tell you what's going on.
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