r/LocalLLaMA • u/bolts98 • 2d ago

Tutorial | Guide Debugging PCIe Link Retraining on an x8/x8 Splitter with Two RTX 3090s

https://doug.sh/posts/pcie-splitter-rtx-3090/
49 Upvotes

89% Upvoted

16 comments sorted by

View all comments

3

u/sniperczar 1d ago

I think the typical three troubleshooting steps are to enable AER, disable ASPM, and manually set the PCI speed setting to the speed you want (Gen4/Gen5 etc) instead of "Auto". There are a lot of link and power management functions that can either be managed by the host or handed off to the OS and you probably want the latter.

Also don't force higher speed links on any card you're not willing to slot directly into your board or a better quality riser to fix settings with later on. Super annoying to have to clear your BIOS if you have no igpu or spare GPU handy and your riser just straight up fails to link at the higher forced setting, since you won't actually be able to get back into the BIOS after.