Quote from: CoM1ner on March 18, 2017, 12:06:23 AM

I am a Windows guy and trying to make the switch to Ubuntu. On my desktop PC with high end specs, Ubuntu runs fine with only 1 RX470 plugged in with a riser.

When I plug in the second RX470 with a riser, the GUI of Ubuntu runs painfully slow. I have tried the AMDGPU-PRO drivers and the ones that come with Ubuntu clean install with no results.

Does anyone know why running 2 GPU's on risers causes Ubuntu to lag while running only 1 GPU with a riser runs fine?

Need more information about the "desktop PC with high end specs". What kind of motherboard it it? How much RAM do you have? How big is your swap disk? Does it have a CPU with onboard graphics? Have you disabled the onboard graphics in BIOS? Have you tried swapping the GPUs around? Have you tried the 2nd GPU in a different PCIE slot?