Need help with freezing and bsod!

[npowers86]

i am in need of some serious help with my pc. it started out a few days ago where the computer would freeze up and i had to restart the pc. but it would not load up to the windows screen. i would have to do a windows repair which would not find an error. then i would restart and it would come to the main windows screen. then after a while it would freeze up again. i installed windows 7 on a new hard drive and it happened again. freezes and blue screen of death sometimes it goes to the windows login and blue screens other times i can login and be on it a few minutes. i tried installing ubuntu (i know just to see what would happen) and it freezes on installation.
does anyone have any idea? i know its not software relating or hard drive since the other hard drive i tried it a working one. could it be ram, motherboard, gpu or power supply? i just wanna know so i can get this fixed. thanks

my specs

i7-870
gigabyte ud3 p55
4gb corsair dominator 1333mhz ram
1 tb samsung spinpoint hard drive
sapphire radeon 4870 1gb
650 watt ultra power supply

my temps on my cpu are high 20's so i know its not overheating. also i wondered if it was the power supply because a while back my agility 3 ocz began blue screening and died. just rma'ed it. that made me thing maybe the power supply. any help would be appreciated! thanks

 

[Twoboxer]

1) You say you did a fresh install of WIndows 7 on a new HD. Your PC ran long enough to complete the install? Or did you do that on a different PC?

2) If you boot into safe mode, does your PC remain stable?

If yes, the problem would seem to be more psu or gpu related - the theory being when Windows tries to use the card in graphics mode, either the power supply can't pump out the power, or your gpu fails.

So let's start with that.

 

[npowers86]

it is on the same pc just a new hard drive. the first time i reinstalled it let me install motherboard drivers but froze when i installed the gpu drivers. then i did another fresh install and it blue screened when i installed the motherboard drivers. the gpu does sometimes get hot, the fan takes a bit to come on so maybe thats it? but also it has frozen when the fan was on and the gpu is about 40c. thanks again

 

[Twoboxer]

2) If you boot into safe mode, does your PC remain stable?