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GTX 295 and multi-GPU questions in general

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Hi, i have read some tests of the Nvidia GTX 295 and also Multi-GPU systems. Some games take more advantage of it than overs. My questions are: 1) In which domains/technics Multi-Core and Muli-GPU are very faster than mono-GPU ? Shaders ? VBO rendering ? ... ? 2) I have a program with a big pixel shader to create a filter. If i have 20 fps with a mono-GPU, can i expect to have 40 fps (or even 35 fps) with a Bi-GPU ? 3) Is there some domains/technics where Multi-GPU could be slower than a mono-GPU ? 4) Does Multi-GPU recquire specific programming technics ? Thanks.

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Speaking from no experience...

AFAIK games need explicit code to deal with multiple-gpu scenarios, so you're not guaranteed to have ANY speedup. You would have to implement a scheme yourself, like rendering the left of the screen on one card, and the right on another. Another would be to render the scene on one, and apply post processing on another.

some slides

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Quote:
Original post by harveypekar
Speaking from no experience...

AFAIK games need explicit code to deal with multiple-gpu scenarios, so you're not guaranteed to have ANY speedup. You would have to implement a scheme yourself, like rendering the left of the screen on one card, and the right on another. Another would be to render the scene on one, and apply post processing on another.

some slides
Those slides don't seem to be talking about today's much improved Crossfire/SLI setups. I believe (but I don't actually have one sitting on my desk) that in a CrossFire/SLI setup, the driver handles the grunt work for you. You won't see a performance increase of 100% (even if you are GPU bound), but you might see 50% [smile]

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The "explicit" part you have to code yourself with SLI (I don't know about Crossfire) is using the Nvidia Control Panel SDK to specify which SLI rendering mode you want (usually AFR). If you don't do this and the control panel doesn't have a profile for your app, it won't enable SLI because it can have very serious performance implications. Therefore the idea is "we won't turn it on unless you'd asked us to turn it on".

Past that, it's all handled automatically. You keep submitting API calls as normal, and the driver handles sending out the GPU commands to whichever GPU.

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This topic is 3196 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

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