|Start with simple power supply diag web page how to's. |
If power supply will stay on then install in system again as you have now. Try the paper clip jump again in system. If powers on then one of two things. Either power supply is not holding on fast enough. (some boards won't return signal fast) or board is doa and won't return signal.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10