PCIe running only at 8x on Asus M5A99X EVO R2.0

[luismenendez]

Hi guys,

I am crazy trying to find a solution for my RX-570 running at only x8 instead of 16x. GFX is PCIe 3.0 but mobo is only PCIe 2.0 x16 when running only one video card (2 video cards at 8x)

Obviously I am using the top slot and the other 2 are empty. I only have a legacy PCI wifi card apart of the GFX

Any ideas about how to resolve this issue? I am pretty sure there is some performance impact for running PCIe 2.0 at only x8

Many thanks!

Other parts are: FX-6300 vishera with a conservative overclock (4.2 with 4.6 GHZ turbo on water, stock volts + offset) with 16GB dual channel, 1 SSD + 1 HDD

 

[pastymuncher]

Pci-e 2.0 8x is the same as pci-e 3.0 4x so there is a significant performance impact. What motherboard is it and is there any option in the bios to fix the slot to 16x pcie-2.0? Have you run the test in GPU-z to see if it changes under load?