HP 255 G4, Maintenance And Service Manual

Page: 54 / 108

Heat sink assembly
NOTE: The heat sink assembly spare part kit includes replacement thermal materials.
Description Spare part number
Heat sink for use in models with discrete graphics memory 813948-001
Heat sink for use in models with UMA 813947-001
NOTE: To properly ventilate the computer, allow at least 7.6 cm (3.0 in) of clearance on the left side of the
computer. The computer uses an electric fan for ventilation. The fan is controlled by a temperature sensor
and is designed to turn on automatically when high temperature conditions exist. These conditions are
affected by high external temperatures, system power consumption, power management/battery
conservation configurations, battery fast charging, and software requirements. Exhaust air is displaced
through the ventilation grill located on the left side of the computer.
Before removing the heat sink assembly, follow these steps:
1. Shut down the computer. If you are unsure whether the computer is off or in Hibernation, turn the
computer on, and then shut it down through the operating system.
2. Disconnect all external devices connected to the computer.
3. Disconnect the power from the computer by first unplugging the power cord from the AC outlet and
then unplugging the AC adapter from the computer.
4. Remove the battery (see Battery on page 28 ).
5. Remove the optical drive (see Optical drive on page 29 ), if installed.
6. Remove the bottom cover (see Bottom cover on page 35 ).
To remove the heat sink assembly:
1. Refer to the following heat sink removal image that matches your computer.
2. Loosen the screws on the heat sink that secure the heat sink assembly to the system board.
46 Chapter 6 Removal and replacement procedures for Authorized Service Provider parts