SLI or not SLI??


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Message boards : Number crunching : SLI or not SLI??

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Profile Cliff Harding
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Message 1368638 - Posted: 16 May 2013, 21:05:23 UTC

I finally was able to get a 2nd EVGA GTX660SC 2Gb card for my i7/950 machine. I've searched thru this forum for any info in SLI and either I got tired of looking or this olde man's eyes are getting weaker despite new glasses, any way I digress, Question is -- Is there an advantage to working units with SLI activated especially using Lunatics?
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Richard Haselgrove
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Message 1368642 - Posted: 16 May 2013, 21:12:50 UTC - in response to Message 1368638.

I finally was able to get a 2nd EVGA GTX660SC 2Gb card for my i7/950 machine. I've searched thru this forum for any info in SLI and either I got tired of looking or this olde man's eyes are getting weaker despite new glasses, any way I digress, Question is -- Is there an advantage to working units with SLI activated especially using Lunatics?

No, no advantage to working with SLI activated.

And no advantage to working with SLI de-activated, either.

Whatever you do, the cards will operate as two separate and distinct GPUs when used for crunching. Just set up the cards as suits you best, whether for a day job or for an evening's gaming. The rest will take care of itself.

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Message 1368913 - Posted: 17 May 2013, 14:23:47 UTC

Not to disagree with Richard, but Ive seen that on certain GPUs and with certain drivers, sometimes, when SLI is active the GPUs get their memory mirrored (or something like that) and then GPU-Z (and also the Afterburner tool) shown that the memory usage was almost twice as bigger, and the crunching speed seems to be a bit slower...

Im not talking only of older GPU/drivers where this was more common, it happened also on my GTX690, with the 314.22 driver which when installed from scratch or instructed to do a clean install, it sets SLI to on by default...
Also, this particular host was a bit laggy when crunching with SLI active.

So, even when SLI should not matter for crunching, it's better to test if that's true for each particular host, and is allways recommend to disable SLI on dedicated crunchers.
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Message 1369071 - Posted: 17 May 2013, 19:27:09 UTC

Certainly the GTX 690 is very sluggish when SLI is enabled, but its far worse when you have two on board, one with SLI enabled, and one wthout
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msattler
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Message 1369318 - Posted: 18 May 2013, 13:15:54 UTC

I thought the SLI issue had gone away using the newer drivers.
But I could be wrong there.
I do remember having to manually disable SLI on my old 295 cards.
I just checked my dual 680 rig, and the setting is not even there.
Might also have to do with the OS involved.....I am running XP on everything but my daily driver.
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Message 1369336 - Posted: 18 May 2013, 13:57:33 UTC - in response to Message 1369318.

You can just try by using this progam:
http://setiathome.berkeley.edu/forum_thread.php?id=71676
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Profile Cliff Harding
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Message 1369839 - Posted: 19 May 2013, 23:00:51 UTC - in response to Message 1369336.

You can just try by using this progam:
http://setiathome.berkeley.edu/forum_thread.php?id=71676



I did notice that my AP tasks were taking longer to run under SLI est. remaining time jumped an addition 20 minutes per, so I attempted to disable it. The NVidia control panel would not allow me to do that under 314.20 because it kept crashing, so the only way to get it to disable was to completely delete the driver and all associated files using Driver Sweeper, and physically remove the bridge prior to restarting the machine. After installing the 314.22 driver everything was back to normal.

Could never get that performance program to work, might be because my data folder in not on the C: drive. Anyway I am running 2 AP tasks per card using cuda50 and it takes approx. 1 - 1.25 hrs. per task. This machine is dedicated primarily to AP unless I run out or get low and the AP splitters are not running. Then I manually adjust to allow other work.
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Message boards : Number crunching : SLI or not SLI??

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