One of the rigs, after running perfectly for one week without hashrate drops, its now beginning to drop the hashrate after a few hours. Again, windows installation is frozen to the same state as one week ago. No updates, no driver changes. This hashrate drop purely caused by another variable affecting the cards. The other twin rig, has no problems whatsoever.
The twin has a monitor plugged in? This happens when the screen goes to sleep, hence people recommend keeping the monitor plugged in at all times or having a hdmi dummy plug?