As far as I know, each version of PCI-E from 2 to 4 doubles the bandwidth of its predecessor. I have no idea how this would translate into performance directly, and I would be a bit surprised if it was a linear relationship. The worst that could happen is it might take longer to generate results.
To what extent is an older PCI-E version (2 or 3, presumably, for an "ancient DDR3 i7") going to act as a bottleneck?
the calculation is done inside the gpu right? i don't think there is much transfer on the pci-e bus with stable diffusion.
If you're using one of the low-VRAM workarounds, a slow bus is going to hurt. But you're already hurting in that situation.
As far as I know, each version of PCI-E from 2 to 4 doubles the bandwidth of its predecessor. I have no idea how this would translate into performance directly, and I would be a bit surprised if it was a linear relationship. The worst that could happen is it might take longer to generate results.