Hey tech enthusiasts,
I’m currently running a ROG Maximus Z790 APEX Encore motherboard with an RTX 5090, and I’ve noticed that the GPU isn’t fully utilizing the PCIe 5.0 bandwidth. What’s odd is that I’m not using the M.2_1 slot, so lane sharing shouldn't be an issue.
Despite having a high-end setup, the GPU seems to be running below the full Gen 5.0 potential. Has anyone else faced similar issues? Could this be a BIOS config, board limitation, or something else?
Would appreciate any thoughts or advice!
#PCIE5 #RTX5090 #Z790APEX #ROG #HardwareHelp #PCBuild #TechSupport
Hello @redstone1590
Thank you for reaching out to us.
May I confirm if your 5090 GPU is currently installed in the PCIEX16(G5)_1 slot? When you noticed that PCIe 5.0 was not functioning as expected, was the PCIEX16(G5)_2 slot also occupied at the time? Could you try installing the GPU in a different PCIe slot to see if it makes any difference?
Also, have you had a chance to test whether switching the CPU PCIe Configuration Mode in the BIOS to [Auto] or [PCIEX16_1 + PCIEX16_2] changes the result?
Kindly share the following information to help us better understand your setup environment:
- the images of the BIOS main page along with any manual configuration settings you may have applied
If possible, please also share the BIOS settings file in .CMO format to allow us to replicate the configuration directly.
- the brand, model and installation slots or ports of the RAM (part number well) and PSU
- are there any extensions or adapters used to connect any devices, such as GPU or SSD?
- two .txt files generated in your Windows system via the steps below:
1) Press WIN + R on your keyboard to open the Run dialog, and type dxdiag → click OK.
2) Click Save All Information and select a save location → click Save.
3) Repeat the same steps with msinfo32 to generate the second file.
Thank you.
Hello ASUS ROG Team,
Thank you for your detailed response and support.
I’ve identified the root cause of the issue: the ALT_PCIE_MODE setting in the BIOS was not set to Auto. After manually disabling it (or setting it to Auto), PCIe 5.0 started working as expected.
Just to clarify:
- M.2_1 was not in use, so it didn’t contribute to the issue.
- The GPU is installed in the correct PCIEX16(G5)_1 slot.
- PCIEX16(G5)_2 was unoccupied during testing.
Everything is now functioning correctly after that BIOS adjustment. Hopefully, this helps others facing similar PCIe detection problems.
Best regards,
