Multi-GPU AER errors traced to MCIO adapters, not retimers or cables
TheZachMueller · x · 2026-09-30
After debugging multi-GPU link errors, the author confirmed the root cause was the MCIO adapters, not the retimers or cables. With the adapters swapped, the system has shown zero AER errors so far, and a link to the adapter used is promised in a follow-up tweet.
A useful data point for anyone building multi-GPU rigs: when facing PCIe AER errors, check the MCIO adapter path before replacing more expensive retimers or cabling.
Related event: MCIO Adapter Card Identified as Root Cause of GPU Server AER Errors(2 posts)→
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