CPU - intel core i5 3450 (4 cores)
Motherboard - intel DH77EB
RAM - 8GB DDR3( two 4GB rams)
GPU - EVGA Nvidia Geforce GTX 560ti, 2GB
Hard drive - 1TB sata
Optical drive - Asus Blu-ray writer
OS - windows 7 ultimate
Power supply - Strike X 600W
when i'm playing games this PC restarts(no blue screens and error messages). Rarely this happened when i was watching movies and browsing internet. Up to now i tried few things which didn't solve my problem.
1.There was no casing cooling fans when i bought this PC. I fixed two casing cooling fans at the back of casing and near the graphic card
2.Disable intel turbo technology and run PC with 2 cores
3.Remove the tick of "automatically restart" in startup and recovery
4.Remove unnecessary devices like dongles,Game pads, etc.
5.I installed CPUz and furmark. Temperatures of GPU and CPU didn't exceed 80C when playing games. At ideal state temperatures were between 35C - 45C for both GPU an CPU. (I live in Sri Lanka. Average temperature is 30C.)
6.There are electricity flucuations in home. First i used DCP 650VA UPS and later prolink 1000VA UPS. Still problem is not solved
I have another problem, but i don't know whether there is a connection with restart. Whenever there is a fluctuation in electricity, UPS gives a small sound, at the same time keyboard and mouse jams for few seconds. For keyboard it's like someone unplug the keyboard and plug it again. I have another PC (core 2 duo) using 650VA UPS but it don't have this problem.
You may still be having a blue screen. By default, windows doesn't really display the blue screen any more, it just records a mini dump and reboots. I would download an app like dumpexam and see if it finds andy minidumps to check.
If not bluescreen then I would suspect a power supply issue. Are you getting enough AMPs to the video card? I am unfamiliar with that power supply.