Hitachi HA810 G3 Series User Manual page 80

5. Attach the heatsink to the processor carrier:
a. Align the pin 1 indicator on the processor carrier with that on the heatsink.
b. Lower the heatsink on the processor carrier until the carrier tabs snap into place.
There will be an audible click to indicate that the heatsink is properly latched on the processor carrier.
79 Hardware options installation