@oblione

4x vegas dual mining with no undervolt? That could be using more than 1200W. Check your consumption because you could be hitting the limits of your PSU.

@syncis

Not sure about cutting down on instances, but for the disk make sure you turn off the recycle bin, and if you're feeling adventurous you could turn off restore points. Each one uses 10% of the drive IIRC. Also the Claymore logs can add up after a while.