pc run for few second then stops then repeats …

When I pressed the on button, it started for a second and then stopped. It then repeated this process every 4 or 5 seconds without me touching the on button again.
before the problem I was have
Intel core 2 duo E5700
Motherbord : G41m sp20 ms-7592
I replaced the cpu by Pentium 4 to try a overclock , but I was stupid because I didn't use a Cooling paste ... the temperature was 95 in bios so I switch of the power quicky then I removed the Pentium 4 and replaced it by E5700 ...
I tried to switch on the power and problem starts...