Many 500 Watt power supplies have split rails and might have issues with keeping up with the power demands. Also the heat generated might not be getting out. I've seen too many systems with both issues.
Beyond that, installing Windows and all that is, in my opinion not consumer friendly. If you restored to factory you have a huge amount of work to get it ready to game.
So i got a EVGA 650TI and installed in my computer, installed all the drivers and such, and ever since i installed it my computer has gone to hell, all my games crash within an hour of playing and then i restored my computer to COMPLETE factory settings, reinstalled windows 7 and tried it again, and now my games wont even load without freezing! its even worse!!! far cry 3 doesn't get past the initial loading screen before crashing/freezing, counter strike GO freezes at the menu and makes a repeat noise until i force shut it down. Im thinking either theres something in my system extremely bottle necking the gPU, or i just got a bad GPU. I dont think its bottle necking because it would at least try to play the games and not freeze before it even got graphically intense. And yes ive checked to make sure nothing is hot, turned down the graphics on everything, and reinstalled drivers. I orded the GPU form newegg and this is my current stock build: pentium dual-core 2.6 Ghz processor, 6GB if RAM, 500w PSU, 500gb HDD, 650TI GPU. All my parts are fairly old but working fairly well also, the only thing i think i might need upgraded is either the PSU or the HDD because Ive wiped the HDD os many times i feel there might be damage to it. anyways..anyone know how to fix this problem or should i just send it back and order a new one?! thank you in advance.