I use Linux ubuntu 16.04 - with the latest driver. the last weeks works everythink fine... now i get only 18. MHS per card (before 27.5) AMD 470
What is the problem? BIOS? DAG?
Have you turned off auto update in Ubuntu? If not, then you probably got an update for the Spectre/Meltdown. Fix ->
https://bitcointalk.org/index.php?topic=2761000.msg28208217