Auto System Powerdown

[imported_shaeng]

I was wondering if some1 can point me in the right direction. I just recently got my hands on an AMD64/MSI K8N Neo Plat/Stock HSF/NXZT Case with PS/etc...It has been running stable since last week when I put it all together and I have even run some BM's and StressTests. All pass and good numbers in range. Well today I came home to find my computer completely powered down and my cable router (LS BFSR41) failed with red Diag lit. I manually turned the machine back on and all is well since (about 4-5 hours). I was wondering if there is anywhere that I can look to find the root cause of the powerdown? (Windows files/logs, etc...)

Thanks,
-shane

I hope this is not the start of a bigger problem and more involuntary shutdowns