For overclock must using AB?

i try Claymore 9.8 -cclock -mclock, this is not stable, the memory suddenly drop to 1000mhz from 2200mhz , and then back to 2200 for few sec then back to 1000

and also anyone tested this driver with 12+ GPU in windows 10, i have 6x570 and 6x580 with ASRock H110 Pro btc, before make me crazy to recognize all 12 gpu in windows 10, not dare to update it