Why is my RTX 5080 running at PCIe x8 instead of x16?

December 9, 2025 2 answers
Asked by TechGuru92
Hey all! I just built my new PC earlier this week, and I noticed that my GPU is running at PCIe x8 instead of x16, which it's supposed to support. I'm unsure why this is happening. Here are the specs: - Motherboard: Gigabyte x870e Aorus Elite Ice - CPU: 9950x3d - GPU: RTX 5080 - RAM: 32 GB DDR5 6000MHz - Storage: - 2TB 990 Pro NVMe (boot drive) - 2TB 990 Pro NVMe - 1TB 990 Pro NVMe - 8TB HDD - 2TB HDD - PSU: 1000W Lian Li Edge

Answers

BuildMaster1
Have you tried checking the BIOS settings? Sometimes you can adjust PCIe settings there. Just double-check your motherboard manualโ€”it should have some details on lane configurations too.
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SmartChip23
Have you checked the motherboard specifications? According to the manual, if you populate the M2B_CPU or M2C_CPU connectors, the PCIEX16 slot will switch to x8 mode. Since you have three NVMe drives, at least one must be in those slots causing the x8 limitation.

QuickFix99: Exactly! That's the likely reason. If you have one NVMe in the M2C_CPU slot, it's definitely affecting the PCIe lanes.

CuriousGamer77: I see. Does this x8 mode significantly affect gaming performance?

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