Dell Inspiron 1428 (Late 2009) - Manual (Page 40)

40 Processor Fan and Heat Sink Assembly
6 Lift the processor fan, along with the cable, off the computer.
7 In sequential order (indicated on the processor heat sink), remove the four
spring screws that secure the processor heat sink to the system board.
1 processor fan cable connector 2 screws (3)
3 processor fan
2
1
3