PCIe Bifurcation on Xeon 8124M (w/C621 AsRock boards)

Quick question for @wendell, @Arpiruk, @Cogito or anyone who has one of these chips:

Does the Xeon 8124M support PCIe bifurcation down to x4/x4 on its CPU connected lanes?

I’m about to pull the trigger on one or two Xeon 8124M CPUs for a SSD NAS with an AsRock EPC621D8A or EP2C621D12 WS.

For it to be more cost effective than EPYC Rome, the PCIe x16 lanes coming off the CPU need to be able to support PCIe bifurcation down to x4. Otherwise I’ll need a card with at least a PCIe x16 switch to bifurcate the lanes, at which point a low core EPYC Rome might be cheaper in the long run.


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I took a peak in the manual for the EPC621D8A and I see it has options to configure link width for the slots, but the manual doesn’t explicitly state what the options are.

Yeup, hence the question. The AsRock manuals do not walk through all the BIOS pages, only the ones connected to their topic headers, so I can’t tell if the bifurcation option is exposed.

Ok, maybe I misunderstood your question. Bifurcation isn’t something the processor does or doesn’t do. It’s a motherboard feature.