Question PCIEX Gen Problem

Nov 9, 2022
A couple of months ago I bought a new PC (i9 12900k, RTX-3090, ASUS ROG STRIX Z690-F GAMING WIFI) and it was/is actually running fine but when I booted it today I did get an "AMIBIOS" screen (with CPU, Total Memory, Detected Storages) and at the bottom it was saying

The PCIEX16 link speed has been modified to Gen3.
This has never shown up before tbh. And I had not changed any HW, moved the PC or did anything else to it tbh. So - not knowing what that meant or how that happened I then went into the the BIOS and under
'Advanced\System Agent (SA) Configuration\PCI Express Configuration" I found:
PCIEX16(G5) Link Speed [Gen3].

I switched it back to Gen5 (I am assuming this was the setting that the first message was talking about?)

The PC booted just fine and it detected my RTX3090 just fine as well.
To test whether the performance had changed or anything else happened I ran 3DMark - Port Royal (which I had run some time ago, just for fun, and I remembered [roughly] the result it scored) and the result was basically the same as the first time. So that's good I guess.

But when I run HWiNFO64 it says
PCIe v4.0 x16 (16.0 GT/s) @ x16 (2.5 GT/s)
GPU-Z says something similar.

I do have to admit that I never ran HWiNFO or GPU Z before.
So I do not know if it always would have said that or if something had changed...

GPU Z has a little tooltip for that field, indicating that this info can be influenced by the power setting of the pc, if that is referencing the windows setting, it's set to performance. And varying part of what GPU Z is showing is always only the second part after the @ symbol. The first part, that has the 4.0 in it, is never higher than 4.0, even if I run 3D Mark.

So, my question(s) basically is/are, if anyone got any insight into this, do I interpret this correctly, that the video card is only using PCIe 4 although the BIOS setting says Gen5?
How could this be? Should I be concerned?

What could have caused the "has been modified to Gen3" message to appear in the first place?