Next time please use a few punctuation maks like comma (,) and/or period (.) it really helps to organize what you write, and make it easy for others to understand.
- Temps are ok then. And for the record I did read that you replaced the thermal paste, but I didn't knew back then if those were idle or load temps.
- Ok, so you got 2x4GB of DDR3 RAM, Have you tried what I wrote and run games with only 1 stik of RAM at the time (to check both stick are fine)?
- Are you using the lastest ndivia driver from nvidia website (sorry I have to make this silly question) ?
- I also read that the PSU is brand new, but it does not change the fact its not from a very well known brand, and just because is new, it doesn't mean its working as intended. But before going for the PSU I will still try look at the other parts first.
- Did someone showed you the GPU working in the PC shop?, it wouln't be the first time a GPU works ok in Windows, but it crash as soon as you try to run a game.