I am minning with RX 470 in 20.560 MH/S but later 4 hours, the hash rate down to 16, why? if i restart claymore it fixed, but i dont want restart! i want run forever :/

any idea?

SO: Windows 7 x64 Ultimate
4 GB ram DDR2
Intel core 2 duo
775 Motherboard
320 GB HDD