My PC has a GTX 1660 Super, an i5-10400F, 16 GB of RAM, games installed on an SSD, and an ASUS TUF Gaming B460M-Plus motherboard. Recently, I've been getting much lower FPS than usual. Kingdom Come: Deliverance, for example, only runs at around 9–15 FPS on medium settings. GPU-Z reports the bus interface as PCIe 3.0 x16 @ x1 3.0, even while its render test is running. I expected it to operate at x16. The graphics card appears to be installed in the upper full-length slot, but the BIOS also reports an x1 connection. What could be causing this, and how can I fix it?
3 Answers
Make sure the card is actually in the upper, metal-reinforced full-length slot. That is the only slot on this board wired for PCIe 3.0 x16. The lower full-length slot looks similar but is connected through the chipset and supports up to x4, while the small slot is only x1.
If the card is definitely installed in the top slot, power the system down and reseat it carefully. Check that it is fully inserted and secured, and inspect the slot and card connector for dust or damage. Also remove any PCIe riser or extension cable and connect the GPU directly to the motherboard.
I checked again and it seems to be in the top slot, but both GPU-Z and the BIOS still show x1.
The slot labels can be confusing, so identify the location rather than relying only on the printed name: the correct slot is the upper one with the metal reinforcement, closest to the CPU socket. After reinstalling the card, run GPU-Z’s render test again and confirm whether the link changes from x1 to x16 under load.
In that case, check the CPU socket for bent pins. The primary PCIe lanes come from the CPU, so damaged socket pins can make a card in the top slot fall back to an x1 connection.