PC Random shutoff/restart no BSOD

[grimtosh]

Hello all, hoping for help with this strange issue:

My computer seems to randomly restart itself at strange times. Sometimes I will be in the middle of a game like WOW or BF4 and others I will be using an internet browser or something and it will restart. It never gives a BSOD just restarts itself. It is not a cooling issue as I have an H80(?) water cooling system, thermal paste, etc with good air flow and cpu temps rarely get over 45-48 C even in bf4. Games and everything run really smoothly and then bam, computer restarts (raid leaders not liking me for this!).

Here is my computer specs:
CPU - FX 8350 (3 months old)
GPU - EVGA GTX 670 FTW 2gb
Ram - 8gb 1600mhz ddr 3 kingston
Mobo - M5A97 Asus
HD - 240gb kingston HyperX SSD (1 month old)
PSU - 700watt Corsair psu (bronze/80+ cert) (3 months old)
OS - Windows 8.1 64 bit

I did not have issues before I installed windows 8 in september; about one month after I put the new cpu, psu and cooling system in the computer. After windows 8 installation, it was about 3 weeks and then this random restarting issue began. I thought maybe it was the psu connection since my apartment has strange wiring so i got an apc 1000w uninterruptable battery backup and it shows all running fine. Neither GPU nor CPU ever get above standard operating temps and didnt look like anything was burned on mobo. It seems like it might be some conflict with win 8 somewhere but i didnt think that the computer would just restart at such random intervals (load or idle, etc).

Any help or insight would be greatly appreciated.

[Deleted]

Is there a pattern in what time it takes for the computer to crash after a cool power up (off for 20min+) -> some heat issue. It also seems that motherboard does not have a off the box support for that CPU, so what version of the BIOS does the motherboard have?