No Post, System LED blinking rapidly after Changing heatsink

[MAdbull]

I messed up with my heatsink about 3-4 years ago. And my System was running without any thermal paste for 3-4 year. As it was running fine so I forgot about this.
But then my System started to stuck at Windows logo whenever I restart it.
And CPU usage reached 100% even on Chrome.
So recently I decided to use a Heatsink and when I changed it, No post and no hdd led. Fans spin and Hard drive is running. PSU also working(also did the Paperclip test, it work).
Changed CMOS led and cleared all dust, Same result
Removed Graphic and RAM and Hard drive, Same result.

And now, the system turn on and off rapidly then turn on for 1-2 minute and turn off and turn on and off and on. But no POST and HDD led

What can be the issue, Is it the CPU or Mobo. I am about to order a CPU but just need a confirmation. Because I cant afford a Mobo.

Specs:
E5700 pentium dual core
Simmtronics G-31(J)
Gt 610 nvidia
WD 500 Gb
450watt psu

No speakers on MOBO

 

[Scibility]

Your CPU most likely got fried after all this use (suprised it took you 3-4 years) it might just be too damaged to boot windows and will shut off automatically because it reached its maximum thermal temperature within the 1-2 minutes you describe.

 

[MAdbull]

Your CPU most likely got fried after all this use (suprised it took you 3-4 years) it might just be too damaged to boot windows and will shut off automatically because it reached its maximum thermal temperature within the 1-2 minutes you describe.

Hi
I ordered a new CPU and played safe with all that static charge stuff.
Thermal paste was there
And I locked the heatsink right

And then I powered on the System and it worked. It reached the windows animation and after that when The system was just getting into Desktop, boom the System turned off.
And all that stuff came back like no HDD led and No post.
After resetting, It works but stopped in windows animation.

I don't know this a overheating issue because I locked heatsink very well.
And one more thing

When I connect my AC plug to the socket, my system turn off for 1 second and then turns off, without pressing power button.
I removed the power switch wire from mobo but it turn on every time for a second.