Computer shuts off after 1 second-installed new MB yesterday

[jamesrwright]

I installed a new LGA1156 MB yesterday..it was running fine-loaded Windows 7 64 bit --clean install....Everything was just fine.

Today I went to best buy and got a a new case case intalled it-now it will not even boot up at all-shuts off after 1 second and keeps rebooting.
Not sure what I am doing wrong here. I installed the old fan and still have the problem. I am very confused-was working fine

I also reapplied the thermal paste earlier-I had put too much on yesterday-I cleaned the processor/heat sink off with rubbing alcohol. I was careful not to get any of the Arctic Fox on the motherboard-I even double checked..

Any idea what to do?

 

[jamesrwright]

I took everything out of the case and reconnected..same thing happens..turns on then turns off. I do not think it can be the PSU-it is only 3 months old-BFG-550W..
I am confused...Maybe it's the new motherboard?

 

[EXT64]

Have you tried running through the boot problems sticky in the Homebuilt section? Do you have any other parts you can swap in?