pc reboots after 3 seconds then stays on no video

This is a custom build that has been working for about three months.

Came back to it and it was frozen. rebooted it and now it does the following.

no bios splash screen
no beeps
turns on for 3 seconds then restarts and stays on with nothing on the screen.


Things i have tried not in order.
replaced power supply
replaced motherboard
tried starting without ram
reseated cpu
tried starting without any cables connected from the case (shorted power pins)
removed video card
reset cmos battery

Still same symptoms. Please give me some ideas of what else i can try

 

You need RAM to start the PC

So it could be the ram itself...



Try some known good ram and see if it works

 

without ram it should beep at you.

 

replaced the processor and the computer works now. How hard is the rma process with intel?