PC turning off at idle

[Honey BaBa]

i recently upgraded my pc with a Gigabyte gtx 650 ti 2gb and also a PSU of 650 watt..
PSU i branded but used and cheap i got it for 7$..
Everything is working awsome for many days but now my pc is automaticly turning off. i dont know whats the problem.. it doesent get of when im gaming at full graphics so it means psu is good?? i also have 1 week PSU warranty left i can change it.. so plz suggest me if you know about this problem..

MP PC
AMD Phenom X4 9650 Quad Core 2.3
4 GB 800mhz ram
3TB hard

 

[c4capricorn]

check ur power settings in windows. also check temps. it does not seem like a PSU problem.