Is SLI faster

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MarkSProject Donor

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Message 1250701 - Posted: 24 Jun 2012, 0:29:26 UTC

Hi,

I have two GTX560 cards and was wondering if it is better/faster to install the SLI link or leave them as two separate cards, they only have 1G of memory so it might be a problem running to many units at once

Thanks MarkS


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Message 1250713 - Posted: 24 Jun 2012, 0:51:56 UTC

Hopefully someone else will chime in here, but I do not believe SLI does much for crunching seti.


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Message 1250718 - Posted: 24 Jun 2012, 1:31:36 UTC

No, for crunching/CUDA, each card is used separately. You must leave SLI disabled - it is only for 3D. Crunching doesn't work in SLI.
With 1 GB per card you can do 2-3 workuints at a time on each.


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Message 1250754 - Posted: 24 Jun 2012, 5:19:33 UTC

With the newer drivers, and I do not know what version changed this, you do not HAVE to disable SLI to crunch Seti properly.
However, I seem to have better results if I do manually disable SLI after installing the cards and driver.


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Message 1250828 - Posted: 24 Jun 2012, 10:40:15 UTC - in response to Message 1250754.

Thanks for that, I have disable SLI and am running 2 task per card, I'll leave it like that for a week or so and see what happens

Thanks MarkS


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Message 1250829 - Posted: 24 Jun 2012, 10:42:10 UTC

Originally, you had to disable SLI to use all the cards, but from 190.38:
- Added support to make all GPUs within an SLI group available for CUDA applications to use.[/b]


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Message 1250882 - Posted: 24 Jun 2012, 15:04:53 UTC - in response to Message 1250829.

what if your card is a GTX 590 or 690, since it is a dual GPU card, is there considered to be an SLI link in the card or is that different?

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Message 1251010 - Posted: 24 Jun 2012, 19:47:51 UTC - in response to Message 1250882.

what if your card is a GTX 590 or 690, since it is a dual GPU card, is there considered to be an SLI link in the card or is that different?


For crunching It dosnt matter if the physical SLI link is there or not, what makes a difference (depending on driver version) is when you have the SLI feature enabled (or not) in the Nvidia control panel.

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Message 1251053 - Posted: 24 Jun 2012, 21:44:17 UTC - in response to Message 1251010.

what if your card is a GTX 590 or 690, since it is a dual GPU card, is there considered to be an SLI link in the card or is that different?


For crunching It dosnt matter if the physical SLI link is there or not, what makes a difference (depending on driver version) is when you have the SLI feature enabled (or not) in the Nvidia control panel.


This is also true for CrossFire on AMD ATI GPUs
(But doesn't the app. 'see' the Compute Capabillity and # of Compute Units,
so it doesn't matter if CrossFire (ATI) or SLI(NVidia) is enabled)?




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Profile Fred J. Verster
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Message 1251093 - Posted: 25 Jun 2012, 0:17:47 UTC - in response to Message 1251053.

what if your card is a GTX 590 or 690, since it is a dual GPU card, is there considered to be an SLI link in the card or is that different?


For crunching It dosnt matter if the physical SLI link is there or not, what makes a difference (depending on driver version) is when you have the SLI feature enabled (or not) in the Nvidia control panel.


This is also true for CrossFire on AMD ATI GPUs
(But doesn't the app. 'see' the Compute Capabillity and # of Compute Units,
so it doesn't matter if CrossFire (ATI) or SLI(NVidia) is enabled)?




Just before a GPU is picked:
Termination request detected. GPU device synched, awaiting termination... 


Can this be the result of an Active Cross Fire state?
Synched by SmartDoctor f.i.?

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Message 1251214 - Posted: 25 Jun 2012, 8:46:35 UTC

No has nothing to do with crossfire in particular.


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Message 1251237 - Posted: 25 Jun 2012, 10:17:25 UTC - in response to Message 1251214.

No has nothing to do with crossfire in particular.

OK, just wondered ;-)


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Message 1251473 - Posted: 25 Jun 2012, 18:51:09 UTC - in response to Message 1250718.

No, for crunching/CUDA, each card is used separately. You must leave SLI disabled - it is only for 3D. Crunching doesn't work in SLI.
With 1 GB per card you can do 2-3 workuints at a time on each.


SLI does work in crunching but it uses the memory from one card not both. You also don't see any speed benefit. You would be better to disable it then leave it running if you are only doing Seti on it.

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Message 1251707 - Posted: 26 Jun 2012, 6:02:27 UTC

I leave SLi enabled on my 670's and it uses both cards. With it disabled I saw no difference in speed or amount of units I could run. The difference is the memory is mirrored card to card(think raid). I run 6 work units just fine this way with 1564MB of memory being utilized both cards maxed at 97% utilization. On lower memory cards it may cause an issue however.


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Message boards : Number crunching : Is SLI faster


 
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