New build random restarts

[Donniepapa]

I'm having random restarts while playing games (swtor, bf3, skyrim) sometimes have had it restart 20 minutes into playing and other times 6+ hours into playing, sometime I can go a week without it happening. Not having heat issue constantly running about 48 C while playing for an extended period of time. I have just built about 3 months ago.

MB-Asus saber tooth 990fx
Processor-amd phenomx6 1100t
Ram- gskill ripjaw x series 8gb (2x4gb)
Power supply-antec cp-1000 1000watt
Vid card-Sapphire radeon 5770 1gb
HD-western digital caviar black 1tb

Not sure what other info would be helpful. First time builder, just lookin for an idea of where to start.

 

[pjmelect]

Most random restart problems that have a hardware cause is due to either faulty memory or a faulty power supply. Test the memory for an extended period of time of a day or more using a memory test program such as memtest86. To check the power supply substitute with a known good one.
If Windows 7 make sure that automatic updates are turned off.

 

[Donniepapa]

ok i ran memtest-no errors, had power supply test found that lines ran to my case fans were putting out low votage so i replaced power supply with a brand new of the same brand. just restarted again 5 minuted into playing assassins creed, loaded back up and was able to play for about an hour no restarts so far. have no idea what it could be