I'm using a Gigabyte B760 Gaming X AX DDR5 motherboard with an Intel i5 12600KF CPU and an RTX 5070 graphics card. My PSU is an RM750E 2025 and I've made sure to use the new cable for the GPU. While testing in 3DMark, I noticed my performance results were off, so I checked GPU-Z. It shows that my bus interface is PCIe x16 5.0 but is running at x8 1.1 without load and x8 4.0 under load. I've checked the BIOS and enabled Resizable BAR, and I'm only using the first M.2 slot which should not affect lane allocation. Any ideas on why this is happening?
2 Answers
It looks like your motherboard is limited to PCIe 4.0, which might be causing the x8 issue. Some boards can end up using fewer lanes based on how slots are populated, so make sure you’re not affecting that. Also, you might want to check if there's an option in BIOS to prioritize full x16 for your GPU.
Just a thought, but sometimes reseating the GPU can help with lane issues too, or trying it in a different PCIe slot if your motherboard allows it. It might make a difference and get those lanes back to x16!
Yeah, I thought it was supposed to be x16. If it's really stuck at x8, maybe a BIOS update could help?