The motherboard has the following shared bandwidth limitations:
You can run the PCIe GPU #1 slot at 16x if you only fill no more than one of the M.2 PCIe 4.0 slots but not the second. This will run the GPU at 16x and the M.2 SSD at 4x on PCIe 4.0.
If you populate both M.2 PCIe 4.0 slots, they will both run at 4x but the GPU is then cut to 8x.
(Naturally, if you add a second GPU they will each run 8x and you can also only use the first M.2 slot. If you populate both GPU and M.2 slots, they run at GPU 8x, GPU 4x, M.2 4x, M.2 4x.)
It looks like I should run GPU #1, M.2 PCIe 4.0 #1, and then M.2 PCIe 3.0 #1 in order to make best use of the available bandwidth. This would run the GPU at 16x and both M.2 drives at 4x.
Just wondering what would the performance impact be like if I got a second PCIe 4.0 M.2 drive and wanted to take advantage of both M.2 4.0 slots, which would cut the GPU speed to 8x. How much is that going to cut framerate or whatever?
This board is a bit more bandwidth constrained than I realized, since the shared bandwidth limitations weren't apparent until I opened the owner's manual. I was assuming I would be able to run two M.2 4.0 SSDs and a single GPU all at their full bandwidth. :\
- PCIe GPU #1 + PCIe GPU #2 + M.2 PCIe 4.0 #1 + M.2 PCIe 4.0 #2
- PCIe GPU #3 + M.2 PCIe 3.0 #1
- M.2 PCIe 3.0 #2 + SATA6G ports 5 & 6
You can run the PCIe GPU #1 slot at 16x if you only fill no more than one of the M.2 PCIe 4.0 slots but not the second. This will run the GPU at 16x and the M.2 SSD at 4x on PCIe 4.0.
If you populate both M.2 PCIe 4.0 slots, they will both run at 4x but the GPU is then cut to 8x.
(Naturally, if you add a second GPU they will each run 8x and you can also only use the first M.2 slot. If you populate both GPU and M.2 slots, they run at GPU 8x, GPU 4x, M.2 4x, M.2 4x.)
It looks like I should run GPU #1, M.2 PCIe 4.0 #1, and then M.2 PCIe 3.0 #1 in order to make best use of the available bandwidth. This would run the GPU at 16x and both M.2 drives at 4x.
Just wondering what would the performance impact be like if I got a second PCIe 4.0 M.2 drive and wanted to take advantage of both M.2 4.0 slots, which would cut the GPU speed to 8x. How much is that going to cut framerate or whatever?
This board is a bit more bandwidth constrained than I realized, since the shared bandwidth limitations weren't apparent until I opened the owner's manual. I was assuming I would be able to run two M.2 4.0 SSDs and a single GPU all at their full bandwidth. :\
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