I recently built a new computer, and the motherboard I have is an Asus Sabertooth x79 (Which I think is too smart for its; own good). Anyway, I have two 7970's (Not Crossfire), mining. When you start the miner, it runs flawlessly, but after everything heats up, around 30 minutes, the computer reboots. I have monitored the Asus Tweaker software, and it seems to do it when the motherboard temperature reaches around 60~61 degrees Celsius.. This is why I think the mobo is too smart for its own good.. But regardless, I have looked for a way to change what temp it does this at, or turn it off entirely, through the BIOS and through the Asus Tweaker program. Any help would be greatly appreciated! Thanks!
I had this issue with a power supply with some sort of feature that would shut it down in case of 'power surges' (temporarily, then it would turn itself back on -- these power surges were probably just 1 amp or less jumps, since I was pulling like 12 to 12.5 24/7..)... Maybe once a month for a 4 or 5 month period, til I replaced it.
your issue sounds diff though... i have an asus sabertooth x58 and have never had any random reboots. a couple of blue screens from initial testing & setting clock too high but that's about it..
ed: my guess would be the psu, or some other power related issue