Message boards : Number crunching : multiple WUs on GTX970 and similar high-end cards
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Some time ago we tested running 2 WUs concurrently on Kepler GPUs, like GTX660Ti. There a clear benefit was observed for short runs, whereas long run WUs lost performance. The reason was that GPU utilization was already good enough, so switching between WUs only introduced further overhead. | |
ID: 39423 | Rating: 0 | rate:
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That's fascinating! I've noticed my heat output on some of these new work units dropping to 45 degrees in cold weather, so I wondered if they were being put to use or what. I wonder if we should all try and make our maxwells more efficient, or if this type of work unit will be crunched away and we'd be at lower output again. Developers, any feedback on what's coming down the pipeline? Is an application update possible, either to swap between two WU packaged within or otherwise increase throughput? | |
ID: 39424 | Rating: 0 | rate:
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The amount of GPU memory is a known factor; if it doesn't have enough memory to run 2 tasks then it will be much slower overall. | |
ID: 39436 | Rating: 0 | rate:
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Note: From my testing, Windows 8 and higher use about 200-250 MB of GPU RAM on any display device, and even more if you have any Modern UI applications running. | |
ID: 39482 | Rating: 0 | rate:
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I have some interesting observation. On my i7-3770K I have a 660ti and a 970 running. I noticed that for some reason the temperature had crept up on the 660ti to about 72C. So I investigated and found that the core frequency kept changing. The GPU load was 95%, memory controller at 41%. Card is overclocked factory 1085 MHz core and 1502 MHz memory. The workunit was a NOELIA_PNP-1-10. It turns out that the card had run up against its TDP. After raising it 108% GPU-Z showed a 105% TDP power consumption. Has anyone had to increase their power target to keep the card from clocking down? | |
ID: 39505 | Rating: 0 | rate:
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Yes, the GTX660Ti and Noelia WUs in general won't benefit from 2 concurrent WUs. And regarding the power limit: the percentage is not relative to the TDP, but rather to the power target. Which is "just" 130 W for normal GTX660Ti's, so it's not that bad. | |
ID: 39540 | Rating: 0 | rate:
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confirmed - been running 2 long WUs whenever I could over the last year using titan and now 970X. | |
ID: 39739 | Rating: 0 | rate:
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Now that I have run GPUgrid for a few weeks, I have come to the conclusion that the tasks are a lot more demanding than E@H. First I had to decrease the overclock on the cards until I added a bit more voltage to the chip to make them stable at the same clock as E@H. Then I found that I needed to increase the power target on the 660ti. I also had to increase the voltage on the Gigabyte 970 to make it stable at the same clock rates I was using for E@H. It has plenty of cooling but still with a GPU load of 91% it runs much hotter than before, 72C vs 56C. This caused me to increase the fan to 85%. I also see that TDP is now around 75% vs roughly 50% for E@H, leading to the extra heat. | |
ID: 39970 | Rating: 0 | rate:
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Yes, GPU-Grid is pushing the GPUs quite hard, pretty much like demanding games. This is not to say Einstein woudln't use them efficiently, but their algorithm is "less arithmetically dense", which means the have to spend more time on moving data around rather than "just" crunching the numbers. | |
ID: 39981 | Rating: 0 | rate:
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Message boards : Number crunching : multiple WUs on GTX970 and similar high-end cards