Odd random shutdown problems

[D3vestation]

I recently upgraded everything in my desktop bought everything from newegg found out i had a DOA mb(wouldn't turn on at all), sent it in and got a new different one Biostar ipower55 now it turns on but it seems like after 5 minutes it shutsdown or when i try and load windows 7 it starts to install but gets like mostly there then the computer turns of completely no beeps or anything shuts down. I was thinking it was the PSU but i got my friends and put it in there and it does the same thing. I really really need some input i can try and provide more details if needed there are the current specs

Core i5 2.66 ghz
4gigs adata ram
Biostar Ipower55
WD 160 gig IDE and WD 500gig sata 3.0
XFX 8800 GTX
Corsair 650 watt psu
Sony sata Combo drive

thanks

 

[MindoverMaster]

Make sure your CPU fan is working.

Make sure all connections are tight.

Try taking out the hard drive, and use a Linux boot cd, see if you have any problems.

 

[Slaymate]

Make sure the heatsink is attached securely to the cpu and the fan is spinning. Are you using the stock heatsink? Did you happen to smudge or smear the thermal paste that came pre-applied to the heatsink? You may need to clean the old paste off and re-apply a fresh coat.

 

[Fazza]

Only connect up the absolute minimum components to see if it's another piece of hardware causing your problem .

Also, go in to the BIOS and reset it to the default settings as when you do this it will look at the components you have installed and set the appropriate settings for them.

 

[D3vestation]

Make sure the heatsink is attached securely to the cpu and the fan is spinning. Are you using the stock heatsink? Did you happen to smudge or smear the thermal paste that came pre-applied to the heatsink? You may need to clean the old paste off and re-apply a fresh coat.

I had to reapply to thermal paste and the fan is working, it also is the stock heatsink

 

[Slaymate]

How much paste did you use? You only want to use a small amount, about the size of a single grain of rice.