IBM x3400 server hanging / chipset & processor heating, but cooling fans are working properly.

Hi,
Make sure that the fans are working at proper speed (not stuck or slow).
Secondly, heat sink could be clogged due to dust or not properly seated. Clean it if required. You may remove it, clean its fins and replace it back (for both processors if required) . Don't forget to apply THERMAL PASTE between the heat sink and the processor (If you remove the heat sink). The Thermal paste conduct the heat from the processor to heat sink which is then dissipated into air by the processor fan. You may also consider adding an additional fan, if required.

Also, place the PC at a well ventilated location so that the cool air enters it from the front and warm air leaves from the back.