This video will demonstrate the replacement procedure of a Heat Sink for the PowerEdge R720.
Replace the Heat Sink: Turn off the system, including any attached peripherals, and disconnect the system from the electrical outlet. When disconnected from the power source, press and hold the power button for three seconds to fully drain the system of stored power prior to removing the cover. Open the system. Remove the cooling shroud.
WARNING: The heat sink and processor are hot to the touch for some time after the system has been powered down. Allow the heat sink and processor to cool before handling them. CAUTION: Never remove the heat sink from a processor unless you intend to remove the processor. The heat sink is necessary to maintain proper thermal conditions.
Using a #2 Phillips screwdriver, loosen one of the heat-sink retention sockets. Wait 30 seconds for the heat sink to loosen from the processor. Loosen the second heat-sink retention socket. Lift the heat sink away from the processor and set the heat sink aside.
Place the heat sink on the processor. Using a #2 Phillips screwdriver, tighten the heat-sink retention sockets. Install the cooling shroud.
Close the system. Reconnect your system and peripherals to their electrical outlets, and turn on the system.