PC reboot loop, strange behavior

[rahulp001]

Hi,
I have a desktop that has been working fine for last 6 year.
Since last week, I see strange behavior.
The pc shuts off automatically. When I push the power button on the pc, it will start for 2 secs and then go in a reboot loop, without anything showing up on the monitor.
Only when I unplug and replug the power chord, the PC will start again and it will stay on for a few hours and then shutdown all of a sudden.
Anyone have this issue and can provide any guidance?

Windows 7.
Western Digital Caviar Blue 500 GB - WD5000AAKS
GIGABYTE GV-R467D3-512I Radeon HD 4670 512MB
OCZ OCZ2RPR800C44GK 4GB PC2-6400 (DDR2-800) DDR2
GIGABYTE GA-EP45-UD3P Intel P45 Core 2
Intel Core 2 Duo E7400
620W PSU

So far I have tried:
1. reseating the memory
2. disconnect and reconnect all power cables from the PSU
3. reseated the heat sink and cpu fan after applying thermal paste

Any pointers will be helpful.

 

[Tradesman1]

Sounds like the PSU is terminal and going to die before long - do you have or can you borrow a different PSU to try?

 

[rahulp001]

Thanks for the response. Ordered one should have it on a day or so. Will try that out and see if resolves the issue. will post back.

 

[Tradesman1]

Will have an eye out for you