Hard to say might be a short in your system or just that you got a bad one that just vent by itself. What was the replacement PSU?
It was shark technology
1x 24pin Main Power Connector,
1x P4 4pin Power Connector,
1x Floppy Drive Power Connector.
3x SATA Power Connectors (on 2 seperate line of cables to reach drives located in various part of the case)
4x Peripheral Power Connectors for IDE drives or case fans.
Complies with INTEL® ATX 12V standard
Super Silence Technology provides best solution for fan noise and heat
High efficiency output
One 12VDC 120mm low-RPM fan
Output short circuit protection (except +5VSB)
Output over voltage protection
Output over wattage protection (620W)
Manual power shut down rocker switch
I am just wondering if the motherboard has diabled the new power supply?