After about 30 minutes the system hung and the warning LED went to solid amber. Still no LEDs on motherboard, -other than the +5. It could be a heat-related problem. Any ideas which hardware it might be?
Use the System Event Log viewer - not Windows Event Log. As the amber light indicates there is something in the event log of the baseboard that will give you insight.
In most cases, this utility is bundled with the firmware download for the board. I cannot find that specific board on the download site. I'll leave it to you to decide if you wrote it wrong, or if the site is just being silly. Meanwhile, you should have a support disc which came with the server, you might find the SEL viewer on that.