How to clean and maintain Acer Aspire 4920 ventilation system

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How to clean and maintain Acer Aspire 4920 ventilation system: crwdns2935265:00crwdnd2935265:01crwdnd2935265:01crwdne2935265:0

Put back heat sink into its right position. Adjust it so that screws lay on their right position.
Screw in order of sequence, from 1 to 4 firmly
Reconnect the fan jack to the fan outlet on the mainboard

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