PC is restarting in a loop every 2 seconds

[Xyb3rNinja]

When I turn on my PC, right after about 2 seconds it shuts itself down automatically and after another 1 or 2 seconds starts itself back up and continues to restart like this in an endless loop until I plug the system out of the wall. The screen is completely black and it doesn't even show the start up BIOS screen of my Gigabyte motherboard.

 

My system is just 11 months old, except for my PSU which was also used in a previous setup and I don't have any overclocked components, not even the graphics card (which is running on factory OC). I first encountered this issue like 2 months ago but it happened only once and somehow got fixed automatically. During that time, I ran numerous tests including mem test and stress testing CPU and GPU but all of them came positive. Now the problem is back again and its been like this for 2 days. 

 

Can someone please give me advice on how to resolve this issue?

 

My system specifications
CPU: Intel Core i5 4570
Board: Gigabyte Sniper B5
RAM: Single stick of 8GB @ 1600MHz (Kingston)
Graphics card: MSI GTX 760 Gaming
HDD: Western Digital Blue 1TB
PSU: Cooler Master GX 550W Bronze (this PSU is 3 years old now, could it be the culprit?)

[jnmbhj]

maybe check out that PSU make sure that its not cutting out. 

[SeanBond]

Ram, reseat it.

[LabRat]

pull the cpu heatsink. make sure cpu is seated properly. reapply thermap paste and reassemble.

 

pull card. boot hooked to motherboard.

[willielikesmonkeys]

Clear CMOS, unplug the system from the wall, take out the bios battery (its a little button cell somewhere on the mobo) then hold the power button for 20 seconds, put back in battery then plug in and power machine back on. 

[Xyb3rNinja]

I already tried clearing CMOS but it didn't work. I'm gonna try replacing my PSU.

[dragoon20005]

sorry didnt ask

 

what cooler you are using?

 

is it the stock cooler?