Question PCIe top slot on motheboard is running at x2 speed instead of x16

[Hypnotik98]

Relevant Specs

-ASUS PRIME Z370-A Motherboard
-GTX 1080 GPU
-Intel i7-8700K CPU

I've discovered the my GPU is only running at x2 speed in the top slot of my motherboard when the slot supports x16 speed.

I have tried the following to fix but no so far have worked.

-Reseating GPU
-Updating BIOS and drivers
-Setting PCIe speeds in BIOS to Gen 3
-Removed all other PCIe devices

I have just tried installing the GPU into slot 2 which also runs at x16 speed and this is now running at x8 speed.

Does anyone know how I can get my top PCIe slot running at x16 speed instead of x2?

 

[rgd1101]

what test did you run to see it running at x2?

 

[Hypnotik98]

It says it both in the BIOS and in GPU-Z, running natively at x2 speed.

 

[rgd1101]

it power saving mode if you are not doing something

 

[Hypnotik98]

it power saving mode if you are not doing something

Ok so is there a way I can turn off the power saving?

 

[rgd1101]

run a gpu benchmark
oc the gpu

 

[Hypnotik98]

run a gpu benchmark
oc the gpu

I've run the render test in GPU-Z and the speed always stays at x2. So is it not in power saving mode?

 

[rgd1101]

and how the result?
could be motherboard or the cpu.

 

[Hypnotik98]

and how the result?
could be motherboard or the cpu.

I haven't tried reseating the CPU, is that worth doing?

 

[rgd1101]

sure. why not. check for bend pin and redo the thermal paste too