Quote from: mealmighty on December 30, 2017, 09:29:06 PM

Hi i have two identical Sapphire 580 RX Nitro + 8GB with Samsung memory in a rig with Asus Prime Z270-P Mobo
I have flashed their bioses with an optimised one and each one of them individually gets 30.8 Mh/s but when both are together one always underperforms and drops to 22Mh/s.

http://prntscr.com/hubno5 <--- screenshot

I tried troubleshooting this by switching the connectors and raisers to each card and also switching their positions on the mobo but each of them in any combination individually gets the max rate but when both together one drops hash rates from 30.8 to 22!

Any idea what could be the problem? I plan on getting 4 more of those and i am afraid if i dont know whats causing this i am about to be in big trouble when i have to run 6 of them and get several of them underperforming.

Regards,
Atanas

Have you disabled CrossfireX for them? that could cause hashrate drop for 2 GPUs...