Help diagnosing motherboard issues

[an51r]

Hey all,

I had a msi p7n platinum 750i and it passed away, powers on but no video the basic death, and I bought a msi neo3 p45 for replacement until my rma was completed. I installed the board today hastily and ended up running a fan cable in between the heatsink and cpu, doh, and ran it three times til it shut off . These were short periods as it did not even get to boot before shutdown, I then comcluded it would be heat that would cause it to shutdown like that and noticed the wire.

Now upon seating the heatsink correctly the board powers on for a few seconds then off and on, off and on, it will not stop cycling until I unplug or turn off the psu. It is not shorting as I have it out on an antistatic bag with only the bare mininum installed, vid card, one stick of ram and the cpu/heatsink.

Do you think the motherboard or cpu is dead? I verified the psu on another PC. I have had many motherboards but never like this. I have never killed a cpu before so wouldn't know if this is common with a dead cpu.

 

[o1die]

Could be the cpu fan wire was damaged, so the board isn't detecting the fan working correctly.

 

[an51r]

I do not think it is the CPU fan wire as I tried to different heatsinks, here is a little more info which leads me to believe if may be the proc, if I disconnect the cpu power the computer stays on and if I remove the cpu fully the computer stays on, the only time it cycles on and off, on and off is when the CPU is trying to be used. I am in the process of trying to purchase a new CPU to test with. I just wish I knew before I spent the money!