Are you running oldkernels? single mining?
No. These are the only parameters I use for the Claymore config. Dual mining was also very stable with only a small amount of invalid shares. 1-2 per 1000 shares max.
-platform 1
-mode 1
-gser 0
-etha 0
-ethi 8
-ftime 3
-r 0
-cclock 1200,1150,1200,1200,1200,1200,1200,1200,1200,1200,1200,1200,1200
-mclock 2050,2050,2050,2200,2100,2100,2100,2220,2220,2220,2100,2220,2050
-powlim -10,-5,-10,-15,-10,-15,-10,-10,-5,-10,-10,-10,-10
-cvddc 950,950,950,850,900,850,850,900,900,900,850,900,900
-mvddc 950,950,950,850,900,850,850,900,900,900,850,900,900
-tstop 75