I know you are a veteran and all, but would you mind posting a parts list to go along with this request like everyone else?
Also, you should take the computer back out of the case and see whether it begins working fine again.
The only thing that is going to be different between outside and inside of the case if all the variables are controlled is a short. However, you won't make it 60 seconds with a short against the case.
Some variable wasn't controlled in the change over process. My initial guess is that one of the RAM sticks came a little bit loose.