Question MSI RTX 4090 Gaming X Trio does not run at PCIe x16 (keeps running at x8) ?

Dec 16, 2022

I purchased a brand new MSI RTX 4090 Gaming X Trio and I just built a computer from the ground up. Motherboard and CPU are also new (specs below).
For some reason which I cannot understand the GPU refuses to run on PCIe Gen 4 x16 and keeps using x8 no matter what. I do not have an NVMe disk inserted in the M2_CPU slot so I don't think my GPU is sharing lanes with something.

What I have tried but still facing the issue:

  • Remove all NVMe M2 disks
  • Fiddle with PCIe configuration in mobo (force Gen 4 or even Gen 5)
  • Clear CMOS, reset default settings on mobo BIOS
  • Update mobo BIOS
  • Reinstall GPU and clean PCIe socket
  • Run render test on GPU-Z to check if GPU switches to x16 under load
What could possibly be the issue? Is it possible there's some defect in my hardware?

Thank you!

My specs if relevant:

  • Gigabyte Aorus Z790 Elite AX (upgraded to latest bios)
  • i7 13700K
  • MSI RTX 4090 Gaming X Trio
  • 2x Samsung Evo 980 NVMe M2 SSDs
  • 1x Kingston NVME M2 SSD
  • Arctic Liquid Freezer II 360
Posting some logs on pastebin for brevity:

System Information: Pastebin - System Information
CPU-Z Logs: Pastebin - CPU-Z Logs

Thanks a lot.