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Message boards : Graphics cards (GPUs) : Question about SLI

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Michael
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Message 20276 - Posted: 29 Jan 2011 | 11:45:51 UTC

Hello,

since I'm planning to get a new computer in the next time, I wondered whether I'm going to buy a single graphics card, or go for an SLI system. I'd like to (at least partially) make this decision depend on the work that can be done with BOINC on the card(s), but I still have some questions left:
- The genereal speed-up of two cards should be 100%, since there are two independent tasks that are computed on each gpu, am I right?
- How about the real ratio? Could somebody tell me, e.g., the difference between a GTX 460 and a GTX 470? If one has 1000 GFlops, and the other has 1300 GFlops, does that mean a total speedup of 30%, or is it much different from just this one value?
- If I buy 2 graphic cars, I'm going to run them in SLI. Is it actually possible at all to run 2 work units (one on each card) if my cards are in SLI mode?

Sincerely,

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Message 20277 - Posted: 29 Jan 2011 | 11:57:28 UTC - in response to Message 20276.

If you have 2 cards, one task will run on each card at the same time. Sli is not used. A GTX470 is much more powerful than a GTX460 at GPUGrid; it does about twice the work. A GTX580 is the most powerful card that works here, then the GTX570, GTX480, GTX470 and a GTX465. I have not seen any results from a GTX560 yet, but I would suggest anyone thinking about buying a GTX560 should think again - just get the GTX570.
Basically if you want to crunch here I suggest you get one of these cards rather than two GTX560's, GTX460's, or GTS450's.

You might want to read this message and the more recent posts in that thread and some other recent threads.

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Message 20278 - Posted: 29 Jan 2011 | 12:06:08 UTC

To answer your question, different cards have different attributes, mainly based on the chip they use. The GTX460 uses a GF104 chip, so it isn't a simple matter of comparing it with say a GTX570 (based upon a GF110 chip). In general a chip with more cuda cores (aka shaders) will out perform one with less. You also have to factor in the speed of the cuda cores as some cards may have less but run at a higher speed.

The GTX460 turned out to be rather a waste for GPUgrid as the science app cannot make use of the 336 cuda cores, due to the gard geometry. It performs slightly worse than a GTX275 (which only has 240 cuda cores).

As for SLI, you will need to disable it as your tasks will fail. If you have multiple cards (or a GTX295) then you can run multiple work units, one per card. SLI can be toggled on and off via the nvidia control panel.
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Message boards : Graphics cards (GPUs) : Question about SLI

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