See if turning down the OC helps. Due to electro-migration the OC a chip is capable of at a certain voltage goes down over time. So you either have to turn down the OC or increase the voltage, which increases the rate of electro-migration and the rate for which your chip will burn out. So it is up to you which you want/can to do. Doesn't have to be it. Could just need to reload your drivers/windows etc...But if turning down your OC help, electro-migration or to much heat are likely the issues.