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Old December 17, 2011, 10:41 PM
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Dead Things Dead Things is offline
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Okay - so here's the story. I have a 24-core Opteron box with a pair of 192 bit GTX460's in SLI. Started testing on stock everything to see if it would be worth putting some effort into. Appears yes, since stock yields something around P6000. Then I try running the 32-bit executable and my score increases by a few hundred (more precise values I cannot recall).

So I think maybe it would run better on a native 32-bit OS, so I install Win2008 IA32 Standard. My physics and combined scores are literally halved and my overall score drops to ~ P4500. Crap, I think, maybe the CPUs are starved for memory addresses - so I install Win2008 IA32 Enterprise and enable PAE so that all 16GB can be addressed. Doesn't change the scores one iota.

So experiment failed, go back to Win2008 R2 Standard and run the 32-bit executable from there, right? Only now, I continue to get the same scores I was getting with the 32-bit OS installed. I cannot for the life of me re-attain the scores I was originally getting with R2 Standard. I've also tried R2 Enterprise, and x86-64 (non-R2) both Standard and Enterprise too. I know everything is the same because nothing hardware-wise has changed and I used all the same driver packages.

Any ideas? I'm about to try Win7 even though it will reduce my cores by half just to see what happens.

Update: Okay, running the 32-bit executable on Win7 x64 brings me back close to my original score at P6000. Where it falls shy (predictably) is on the physics test and combined test. My physics score is now 5200 with 12 cores on Win7, whereas it used to be about 6500 with 24 cores on Win2008. Would be nice to get this performance back from Win2008 so that I could use all my cores to up the physics and combined test scores.

Update 2: I have a hunch it's related to the power supply (I normally run this rig with just the onboard video). Will try daisy chaining another supply in to handle the GPUs and see what happens...

Update 3: P7100 is the best I could do with my GTX460's. Had to be done on Win7, too - not sure why but I was never able to replicate my initial performance with the Server OS's.
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Last edited by Dead Things; December 18, 2011 at 11:32 PM.
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