I'm trying to set up additional storage for my home media server/gaming machine and ran into some issues with a PCIe M.2 expansion card. Here's my setup: I have an R9 7900X CPU, an XFX RX7900XTX GPU, an ASUS ROG STRIX B650E-F motherboard, and G.SKILL 32GB RAM. My motherboard has all its SATA ports filled with HDDs and all three M.2 SSD slots are occupied. I bought the ASUS Hyper M.2 X16 PCIe 3.0 X4 Expansion Card, which I installed in the second PCIe slot. However, while I can see one out of the two M.2 drives on the expansion card when booting, the other isn't recognized.
I checked the BIOS, but I didn't find an option to bifurcate the second x16 slot, and I read that M.2 slot 3 can't be used simultaneously with the second PCIe slot. I'm pretty confused about what's going wrong here and how to start troubleshooting since I've found little information online. Can anyone help?
1 Answer
It seems like you might be hitting a limitation of your motherboard. If the BIOS doesn’t have an option to bifurcate the second slot, that usually means what you're trying to achieve isn't supported. The second PCIe slot might only provide x1 electrical lanes instead of x16, which is what you need for running multiple SSDs efficiently. If you look at the specs for your motherboard, it’s clear that only the first PCIe slot is x16 electrically; the others can be misleading as they’re x16 only mechanically.
Ah, that makes sense! I thought mechanical and electrical specs were the same. Should I swap my GPU and expansion card, or would that bottleneck the GPU too much?