DrSuSE wrote:
In most cases, x16 should be probably no or minimal benefit over x8, I think... but... it just bothers me that it's not working the way it's supposed to.
True, even the 4090's probably can't use over x8 in most cases, but I concur -- it SHOULD work and it would drive me crazy if it didn't!
One dumb question here... You are using the TOP pcie slot for the graphics card, right? I'm sure that's the case but it hasn't been explicitly noted here. The next slot down will only run x8. Only the top slot, "PCIEX16(G5)", will do x16 (and only when M.2_1 is empty).
At this point, if both the 3090 and 4090 result in x8, it seems the GPU cards are ruled out. And you've reset bios/cmos, so settings should be ruled out. And the x8 is apparent in the bios itself, so that rules out windows/drivers.
All that's left is the motherboard and perhaps the CPU and/or socket. You could try inspecting the socket/pins and reseating the CPU, but that's a hassle remounting the cooler. A bad pin connection COULD cause this, but it's a long shot especially given that your boot drive worked fine in M.2_1.
So I'm out of ideas. Again, you might post on the "600/700 series motherboard" forum (and perhaps reference this post, so people can see what was already tried). Someone over there may have another idea.
-----------------------------------------------------------------------------------------------------------------------------------------------------
Z690-E, i9-12900k, 2x16 DDR5, 980pro nvme x3, Ryujin-II 360, Strix Animate-II, Evga 3090 ftw3