Error on screen:
HyperTransport error caused a system reset Embedded I/O Bridge Device 2
SEL will show:
Chipset Err: Critical Event Sensor PCI Err (BUS 0 Device 7 Function 0) was asserted
There is a discussion about it here (with no real solution):
I replaced both power supplied with known good units from a Dell 2950. No effect.
My SEL was filled with these errors and, obviously, my server was rebooting frequently.
I noticed NO similarities or triggers. OS did not matter, CPU load did not matter, disk activity did not matter, etc etc.
THE SOLUTION THAT FIXED THIS ISSUE WAS A REPLACEMENT MOTHERBOARD FROM DELL. THE ORIGINAL DESIGN IS CURSED.