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Message boards :
Problems and Help :
multiple GPUs
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 EA6LESend message
Joined: 4 Feb 21
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ID: 1345478
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Hi!
I just added a second GPU RTX A2000 to one of my crunchers, both GPU are identical and the second one is about 6 times slower than the first. is there a setting that I need to change for the second GPU to be fast as the first one? at the moment I am crunching AP27 with the GPUs.
Thank you,
Marius | |
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Looking at your host, all the times are about the same. Where are you seeing the 6x difference?
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Eating more cheese on Thursdays. | |
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EA6LESend message
Joined: 4 Feb 21
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ID: 1345478
Credit: 2,131,147,779
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The machine with 2 GPUs is DC3 and has this results for GPU:
AP27 Search DC3 - 41 19 46.34 3,301 / 865 / 53,019 1,052 / 804 / 5,316 1 / 1 / 2
The first GPU has 804s and second GPU has 5316s | |
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EA6LESend message
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this is one of the units processed by the second GPU :
https://www.primegrid.com/workunit.php?wuid=903413568
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EA6LESend message
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I see errors as well on that GPU.
https://www.primegrid.com/workunit.php?wuid=903185564
the GPU was installed about 4 hours ago. | |
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Two ideas on possible causes of the slowdown:
1) Heat causing the second card to down clock. What are your temps?
2) 2nd GPU not in a full PCIe slot (x16), but in a smaller slot (x1 or x4)? Keep in mind that some motherboards will divide PCIe lanes when more than 1 PCIe device is in the same set of lanes. Usually, this would divide both GPUs (i.e., 1 x16 slot install slows to 2 x8 slots with two GPUs as the lanes get divided), but it can occur otherwise (e.g., 1 x8 slot divides across 2 x4 slots when second GPU shares those lanes with something like a PCIe NVME board, etc.).
If 1, work to reduce heat. If 2, you need to be in a different slot, or if none available, will need to look at a different motherboard.
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EA6LESend message
Joined: 4 Feb 21
Posts: 9
ID: 1345478
Credit: 2,131,147,779
RAC: 2,518,014
|
Two ideas on possible causes of the slowdown:
1) Heat causing the second card to down clock. What are your temps?
2) 2nd GPU not in a full PCIe slot (x16), but in a smaller slot (x1 or x4)? Keep in mind that some motherboards will divide PCIe lanes when more than 1 PCIe device is in the same set of lanes. Usually, this would divide both GPUs (i.e., 1 x16 slot install slows to 2 x8 slots with two GPUs as the lanes get divided), but it can occur otherwise (e.g., 1 x8 slot divides across 2 x4 slots when second GPU shares those lanes with something like a PCIe NVME board, etc.).
If 1, work to reduce heat. If 2, you need to be in a different slot, or if none available, will need to look at a different motherboard.
The machine is a thinkserver with 2 processors, the PCI slots are separated in two lanes, one for each processor. and the cards are also on one port from each lane.
heat should not be a problem as the cards are far away from each other and there is a lot of air being circulated. I will connect the monitor to the server to see the temps, in the remote desktop the GPUs are disabled and can't see how stressed are.
I will report probably tomorrow again. might change the video card on another PCI slot as a test. | |
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EA6LESend message
Joined: 4 Feb 21
Posts: 9
ID: 1345478
Credit: 2,131,147,779
RAC: 2,518,014
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this is the spec of the server:
https://psref.lenovo.com/syspool/Sys/PDF/ThinkServer/ThinkServer_RD650/ThinkServer_RD650_Spec.PDF?v=1ea46df3-85b0-4b1e-ab5c-3a4c3e1248ce
The second card is on slot 8 | |
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EA6LESend message
Joined: 4 Feb 21
Posts: 9
ID: 1345478
Credit: 2,131,147,779
RAC: 2,518,014
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Got it solved. all the PCI slots on the second processor were 8x. I had another server with one 16X for each processor and I switch to that one for now. both GPUs are working well :) | |
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Problems and Help :
multiple GPUs |
