Check your SATA/RAID drivers. The stock ones may cause rebooting and such. There's information earlier in the thread about this and is what caused me to have reboots during OS installation.

I discovered yesterday that I'd been having significant problems reading from and writing to my harddrives (a couple hundred errors in early February and several hundred yesterday). My initial thought was that it was a harddrive issue, but as it was happening on multiple drives, my attention turned to RAM or motherboard. Today, I came home to find that the computer I had left running while I was out for the day was powered up and dead, and no amount of effort will get it to POST, even with cleared CMOS. This motherboard has been little but trouble for me, and while I am often happy with the results I get out of it, it is not worth the blue screens, random rebooting, various quirks, and high failure rate that I've experienced and have been suggested by others' posts in this thread. I hope no one else is suckered into purchasing this unreliable board; it certainly hasn't been worth the money I put into it last year and I'd hate to see more people deal with the various problems it presents.