PC boots but then shuts down midway of booting

[mannrak2003]

or after a few seconds after successful booting.My config is as below:

intel Q8200 quad core
MSI P-45 Neo-F
kingston 2 GB *2 DDR2 RAM
Corsair VX-450
APC EN550 UPS
Palit graphics card(Just don't remember the model number of the card.)
Dell 19" LCD monitor.(Again don't remember the model no:.typing from a friend's place..
Zebronics Bijli Cabinet.

Sometimes it boots successfully.but shuts down after some time.then powers up automatically only to shut down once again.again and again this continues until the power is there in the CPU but no signal comes to the monitor.

I removed all connections inside and outside the motherboard and reapplied them.The CPU was showing a high temperatures of 72 degrees inside the BIOS hardware monitor when this problem first occurred.

Then I removed heatsink and CPU,removed thermal compound using isopropyl alcohol and reapplied it once again.Then CPU temp showed up as a stable 42 degrees when I last checked in BIOS hardware monitor.So its not problem with CPU.So is it a problem with the SMPS,UPS or motherboard.Please advise.Or is it a problem with a loose connection on the power switch on the cabinet.?

Please advice ASAP.

[Prime_Coder]

I think there must be problem with the SMPS unit. It happens because of overheating. If the problem persists even after reapplying the thermal paste, then you will need to get a good SMPS unit.

[mannrak2003]

OK.THe Corsair VX 450 has 5 years warranty as and when I bought it in December 2008.Whats the procedure for replacement or RMA?Is it through Kaizen InfoServe?
What do I need to do?Just put the SMPS into the original packing and give it to the nearest Kaizen service center.The nearest one w.r.t my location is at Cochin as per their website?How many days does it usually take for the replacement?