RTX 5080 negotiating PCIe Gen5 x8 instead of x16 after exhaustive BIOS testing

[Hectorpr]

Hello everyone,


I am posting a detailed troubleshooting report in hopes that someone can identify what I may have missed.

Hardware​

Motherboard:
ASUS TUF GAMING Z790-PLUS WIFI


CPU:
Intel Core i9-14900KF


GPU:
ASUS ROG Astral RTX 5080 DOOM Edition


Memory:
Corsair DDR5 6000 CL36


Storage:
Samsung 990 Pro 2TB


BIOS:
1836

---

Problem​

GPU-Z consistently reports


PCIe x16 5.0 @ x8 5.0


even during GPU-Z Render Test.

---

BIOS configurations tested​

• Intel Default Settings
• ASUS Advanced OC Profile
• Auto
• XMP I
• XMP II
• OC Tuner I
• XMP I + OC Tuner I
• XMP II + OC Tuner I

No configuration changes PCIe lane negotiation.

---

Memory verification​

Verified with CPU-Z


DDR5-6000


36-44-44-96


Memory is stable.

---

GPU verification​

Render Test running.


GPU remains PCIe x8.

---

Remaining possibilities​

• Physical seating
• CPU socket pins
• Motherboard PCIe slot
• GPU hardware

I appreciate any technical insight.

 

[Solaris17]

I would have reseated as step 1, followed by different slots if possible.

Make sure the card is not sagging and the rear of the card is seating correctly in the slot.