Thank you. Will try some of thouse. And about the tstop 75 is just additional, the cards are running mostly around 55c
The ULPS was already checked.
edit: Seems to be more stable with the ethi 4
edit2: not dual-mining
1160/2020
Honestly, if you have stability issues at anything above ethi 4, I think you have another problem. I've built over 20 rigs, all downvolted and optimized, they all run ethi at full speed and dual mine. I never have this 4Mh/s issue.
Set your core clock to 1100, 1160 is just not necessary. Also open up a HWinfo and check your cards for memory errors at 2020 frequency. If you have bazillions, then you will need to downclock the memory. Also, I don't know what brand of memory you have on your cards?