Why are my ASUS LC RTX 5090 and my M.2 in the main M.2 slot below the GPU only at PCI-e 4.0x with the 9914 BIOS. Only other M.2 is on the M.2 add-on card and the only settings set in BIOS are the GPU and M.2_1 at 5.0. GPU-Z says the 5090 supports 5.0...

I can't boot into BIOS right now to get the right settings, but I think where you set the 16x/8x for the PCI-e lanes for the GPU etc., look in those settings. For M.2_2 enabled I'm pretty sure your GPU needs 8x, not 16x, and there might be another op...

It is an Apex, and I figured out I can only utilize one Gen 5 in M.2_1 and need to put my other two M.2s in the add-on card, I think.

I thought if you put your Gen 5 M.2s in M.2_1 and M2_3 you get your GPU 16x, it's only 8x. Can you use only M.2_1 for GEN 5 to keep 16x on GPU?