Folding Forum

Just some napkin math: each lane of PCIe 3.0 is a touch shy of a gigabyte per second of bidirectional throughput (eg it can be transmit, or receive, or both at the same time at the full ~985MB/s.) Meaning, at least in theory, a PCIe 3.0 x4 slot would be able to manage, with some to spare, the throughput needs of @arisu's GTX970M.

Part of me wonders if that particular project was perhaps VRAM heavy? Most of the 970M's were shipped with 3GB of VRAM, so maybe combined with the compute kernel and dataset, it needed to continually page in the data? That seems unlikely to be honest, but I can't imagine why else there would be a continuous stream of 3GB/sec to a 3GB VRAM card. Would be interesting to see that same WU on a card with larger VRAM, just for A/B comparison sake on the PCIe throughput.

ViTe wrote: ↑Sun Sep 28, 2025 2:03 am

CaptainHalon wrote: ↑Wed Sep 03, 2025 3:19 pm
But for what it's worth to anyone, I also (surprisingly) noticed quite a difference going from x8/x8 pcie 4.0 to x8/x8 pcie 5.0. At least 2-3m PPD on the combined total for both cards. These are trends I've noticed over multiple days. So take it with a grain of salt if you will, but from what I'm seeing it matters more than I would have thought.

Something else changed, like OS, SATA/NVME or something in BIOS.
I tried RTX 2080 with pcie2.0 x8 and pcie3.0 x8. Found no difference in PPD.

Negative, ghostrider.

I have run my 5070ti on a PCIe v.3 (10400 i5) and noticed about a million PPD drop from PCIe v.4 (5600X). That was not for very long so it might not be accurate. Right now I'm seeing 14-16 million PPD from it with the Ryzen 5 5600X on Win 11.

Maybe not really relevant to modern cards but...
I tried same GTX 1660Super with 3 generations of PCI-E: PCI-E 3.0 x8, PCI-E 2.0 x8 and PCI-E 1.0 x 16 and PCI-E 1.0 x 4 (!)
Only PCI-E 1.0 x 4 showing 5%-10% lower PPD but it's second card in the system and running a bit slower