Win 7 64 bit, power save option was on for all of them but never had any issues with my other single, using a corsair 750w psu motherboard ASUS M3N78-VM and i'm using cgminer I'm noticing its not becoming unrecognizable now that i'm using a second batch file but it still will shut itself off after about 4-6 hours of mining and having to restart cgminer.
If the problem is resolved by restarting cgminer, then it's not the unit. This can be either cgminer failing, network problem or your computer trying to go on standby
or partially tries to turn itself off. Also, are you using a virtual machine?
BF Labs Inc.