Question PCI Express x4 slot running at x1


Apr 20, 2013
I have an Aorus Ultra Z390 board. When I plug a GPU in the x4 slot, it runs at x1. Here's what I tried:

  • I have 2 GPUs, and they both run at 16x on the 16x slot, and 8x on the 8x slot. Both run 1x on the 4x slot.
  • I removed everything but the CPU and RAM sticks from motherboard. No m.2 drive or anything else that shares PCI EX bandwidth. Still happening.
  • I reseated the CPU.
  • Checked for bent pins in the CPU socket, it's a brand new mobo, everything's good. No bent pins.
  • Sprayed some air into the PCI Ex 4x slot to clear any dust.
I can see the GPU running at 1x while plugged in the 4x slot in the BIOS. So it's not an OS thing.

The only thing I can think of is that, I really need to push the GPU to get it into the 4x slot to hear the lock click because part of the GPU gets on top of some mobo connectors like case front panel connectors and USB headers. Maybe too much force pushing down bent something? I don't know if that would cause a problem.

Any ideas are greatly appreciated.


Feb 10, 2013
Don't push it down too hard, it'll risk you damaging the hardware. Once the card is locked, all of it's pins are in contact and it should run at the specified bandwidth.
The things you've tried should've solved the problem. Yep it's not an OS thing, it might have something to do with the BIOS settings/config.

Might be that the motherboard's configured to share that slot's bandwidth. Even if you remove the m.2 drives, but still specify bandwidth for that slot, the board shares it (atleast on my board it's that way)

One simple idea is to save your current settings as a profile and reset the BIOS by removing the CMOS battery or by shorting two pins if they're there on your motherboard.
That might clear any settings and could get it back to 4x.

Otherwise, in summary, it's either that
• GPU isnt making proper contact physically, or
• The mobo is configured to share bandwidth from that slot to either SATA or m.2 or something.

And anyway, if you have 2 GPUs and 3 PCIe_x16 slots, why use the 3rd one? Use the 1st and 2nd slots, and any other PCIe_x16 card in the last slot because it's better if the GPUs have more bandwidth.