4 x R9 390 strix 8g Overclock No Voltage GPU tweak 2 for OC GPU Clock 1135 Mhz, +o mV, Memory Clock 6000 Mhz, Power target 150%,  After 6 months mining the hasrate drop from 129.2 Mh/s to 128.7 Mh/s, there is a risk with Overclocking long term card degradation and drop hasrate ? Temperature between 65 ° C to 72 ° C, connection with pool is ok, I have 6 months ago in mining ETH, ETC, ZEC with claymore V 8.1 ..