Used PCIe Bandwidth

spartin503 · October 31, 2013

So, I was curious about how much of the PCIe bus is actually used. So I did some research and couldn't find anything conclusive. I was just looking for the theoretical max bandwidth that a graphics card would use, running at full load. Is there anyway to calculate it?

Eddyall · October 31, 2013

Well Linus tested some GTX590 and AMD6990 in quadSLI and CrossFireX and found that at 4x 2.0 he lost like 2 or 3 FPS over 16x and 8x so anything that's over 8x 1.0/4x 2.0/2x 3.0 would be fine.

I can't even find a RAID card with 16x whatever version on Newegg so it's probably fast enough that you should care unless it's a PCI-e SSD.

It would be fun to know but if they're something why didn't he used it for the video.

Godlygamer23 · October 31, 2013

Video cards use all the bandwidth available. However, you hardly get any benefit from having a faster PCIe bus. In situations like 690s, PCIe x16 slots effectively become x8 per GPU. Putting a 690 on an x8 slot effectively makes each GPU get x4 speed. On PCIe 3.0, this will equal 8GB/s per GPU which is plenty of bandwidth for them at this point.