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Difficulty: MediumLaptop Hardware Components and Upgrades

A field technician is replacing a noisy, failing CPU cooling fan and heat sink assembly inside an enterprise laptop. Place the following service procedure steps in the correct chronological order from first to last.

  1. 1Shut down the laptop operating system completely and unplug the external AC power adapter.
  2. 2Remove the bottom enclosure base cover and disconnect the internal battery cable from the motherboard header.
  3. 3Unplug the fan power connector and loosen the captive retaining screws on the heat sink assembly.
  4. 4Remove the old thermal assembly, clean residual thermal compound off the CPU die using isopropyl alcohol, and apply fresh thermal paste.
  5. 5Mount the new thermal assembly, tighten the securing screws, plug in the fan power cable, and reconnect the internal battery cable.

Answer

The correct service sequence is: 1) Shut down laptop and unplug AC power, 2) Remove base cover and disconnect internal battery, 3) Unplug fan connector and loosen heat sink screws, 4) Remove old thermal assembly, clean CPU surface, and apply fresh thermal paste, 5) Mount new assembly, reconnect fan header, and reconnect internal battery.
Safe laptop servicing requires isolating external AC power first, followed by removing the base cover and immediately disconnecting the internal battery to eliminate standby electrical energy. Next, fan electrical leads and heat sink fasteners are released so the old unit can be removed. The CPU die surface must be thoroughly cleaned of old compound and refreshed with new thermal paste before securing the replacement thermal module and reconnecting power.

Step-by-Step Solution

1
Perform a complete system shutdown and unplug the AC power adapter from the laptop power port.
The device is disconnected from external electrical mains.
Protects the technician and components from live line current before opening the enclosure.
2
Unscrew the bottom panel, lift off the base cover, and detach the internal battery connector from the motherboard.
Residual standby voltage on the motherboard is safely isolated.
Prevents electrical shorts on active board traces when handling metallic tools or components.
3
Disconnect the cooling fan wire harness from the motherboard header and loosen the captive screws securing the heat sink in reverse numerical order.
The fan cable and heat sink module are released from the system board.
Prevents physical damage to delicate fan headers and ensures even tension release across the CPU die.
4
Lift out the thermal unit, clean off hardened thermal interface material using a high-percentage isopropyl alcohol wipe, and apply a small dot of new thermal paste to the CPU surface.
The CPU heat-transfer surface is clean and prepared for the replacement heat sink.
Reusing old thermal paste leaves air pockets that cause rapid CPU thermal throttling and overheating.
5
Align and seat the new fan/heat sink assembly, tighten the mounting screws in sequence, plug the fan harness into its motherboard header, and attach the internal battery cable.
The internal cooling replacement is completed and power is restored to the system board.
Ensures complete hardware integration and thermal contact prior to replacing the bottom base cover.

Key Concept

Laptop Hardware Disassembly and Thermal Module Upgrade Sequence
Estimated Time:1m 30s
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Topics

Laptop Hardware Components and Upgrades

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