CUDA & SLI

Author	Message
YoDude.SETI.USA [TopGun] Send message Joined: 19 Jul 05 Posts: 9 Credit: 826,961 RAC: 0	Message 909889 - Posted: 21 Jun 2009, 17:28:54 UTC Ok, I get that running GPUs in SLI are only seen as a single GPU instead of two or more while running SETI. My question being...When running CUDA WUs on an SLI enabled system, do the GPUs work in tandem to crunch out the work as they do while gaming? Yo- ID: 909889 ·

Andy Williams Volunteer tester Send message Joined: 11 May 01 Posts: 187 Credit: 112,464,820 RAC: 0	Message 909945 - Posted: 21 Jun 2009, 21:42:06 UTC - in response to Message 909889. No advantage. Each work unit requires its own GPU. -- Classic 82353 WU / 400979 h ID: 909945 ·

Gundolf Jahn Send message Joined: 19 Sep 00 Posts: 3184 Credit: 446,358 RAC: 0	Message 909960 - Posted: 21 Jun 2009, 23:25:48 UTC - in response to Message 909945. No advantage. Each work unit requires its own GPU. That wasn't the question. Is one task crunched faster with two GPUs in parallel? GruÃƒÅ¸, Gundolf Computer sind nicht alles im Leben. (Kleiner Scherz) SETI@home classic workunits 3,758 SETI@home classic CPU time 66,520 hours ID: 909960 ·

Lint trap Send message Joined: 30 May 03 Posts: 871 Credit: 28,092,319 RAC: 0	Message 909970 - Posted: 22 Jun 2009, 0:38:00 UTC Last modified: 22 Jun 2009, 0:40:38 UTC Maybe if the answer is stated differently, there is no wu sharing among GPU's in SLI mode. One GPU will crunch, the other/s will sit idle. [/edited/] Martin ID: 909970 ·

razamatraz Send message Joined: 23 Oct 07 Posts: 142 Credit: 27,815,748 RAC: 0	Message 909971 - Posted: 22 Jun 2009, 0:42:00 UTC - in response to Message 909970. Correct me if I'm wrong. If in SLI you will get only 1 GPU working so your crunching speed will be the same as if you only had one card. If you disengage SLI you will get both cards crunching separate units effectively doubling your speed, although each unit will still take the same amount of time. This is what I've learned...hopefully I'm right. ID: 909971 ·

Lint trap Send message Joined: 30 May 03 Posts: 871 Credit: 28,092,319 RAC: 0	Message 909974 - Posted: 22 Jun 2009, 0:50:09 UTC - in response to Message 909971. You are basically correct (AFAIK). Multiple GPU's crunching will require the right apps to be installed, which is discussed in other threads. Martin ID: 909974 ·

Andy Williams Volunteer tester Send message Joined: 11 May 01 Posts: 187 Credit: 112,464,820 RAC: 0	Message 909998 - Posted: 22 Jun 2009, 3:04:54 UTC - in response to Message 909971. You are absolutely correct. SLI is a complete waste of GPU processing power. Clear enough? -- Classic 82353 WU / 400979 h ID: 909998 ·

YoDude.SETI.USA [TopGun] Send message Joined: 19 Jul 05 Posts: 9 Credit: 826,961 RAC: 0	Message 910056 - Posted: 22 Jun 2009, 7:40:01 UTC - in response to Message 909970. Maybe if the answer is stated differently, there is no wu sharing among GPU's in SLI mode. One GPU will crunch, the other/s will sit idle. This was the answer I was looking for. I did some of my own testing with SLI enabled/disabled and found this to be true. I was hoping otherwise however. I probably should have just done my own testing and not bother to post this question, but I appreciate everyone's reply's. Thx guys, Yo- ID: 910056 ·

SpeedMax Volunteer tester Send message Joined: 23 Feb 00 Posts: 12 Credit: 598,744 RAC: 0	Message 912099 - Posted: 27 Jun 2009, 17:33:07 UTC - in response to Message 909945. Hi Andy,I have two GPU cards inside my PC not in SLI configuration It performs just one CUDA task at time. How can I see if both GPU cards are working? Or it must work two CUDA tasks at time to let both GPU cards work on SETI? max ID: 912099 ·

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