HP ProLiant DL360 G7 hangs at "Power and Thermal Calibration" screen

So, after bringing a third system into the mix, and experiencing the same issue, we began to question the environment. I dug up a copy of the HP ProLiant Servers Troubleshooting Guide and found the POST problems flowchart shown below.

Carefully running through the steps in the chart, we realized that the one constant across all of the servers was a KVM switch attached to the data center crash cart. This was a consumer-class USB-enabled KVM. As per the highlighted node in the flowchart, Do you have known good KVM?, I could not answer conclusively.

So, we unplugged the servers from the KVM switch and ran an automated boot, sleep 300; reboot sequence in rc.local. The servers had no issues with this, regardless of the normal DIMM, low-voltage DIMMs, PSU wattage, etc.

This was all the result of a poor interaction with a USB KVM switch. By virtue that this was the console, it ensured we'd see the failure if we were looking for it. Self-fulfilling...