I got two of these and I'm not sure if I got one unusually good one or one unusually bad one. I'm not using a hub at this point have them each plugged into a separate windows machines, one out of the box stable for days, upped it to 700 and still stable for days, haven't pushed much beyond 700. The other is a different story, doesn't stay hashing for more than at most 2 hours. Stock voltage on both was 0.755. On the problem child I tried adjusting down, had best results around .721 (stayed on for 2 hours) wouldn't even start hashing at anything less than 0.67. I've tried swapping the good one and the not so good one onto various machines and the good one always stays good and the not so good one always drops out. Anything else I should check?