Can you help me specifically or just share demagogic advices?
It's not demagogic. Any parameter can be set like
-mclock 1250
for all devices or
-mclock 1250,0,1100 for each device individually. 1250 for 1st GPU, didn't change for 2nd GPU, 1100 for 3rd GPU etc.
Ask what you have for set for your devices and i can help you if you can't do that.