Dell Vostro 15-7580 Owner's Manual page 36

4 To remove the heat sink assembly:
a Turn over the system board and remove the six (M2x3) screws (6 > 5 > 4 > 3 > 2 > 1) that secure the heat sink assembly to the
system board [1].
NOTE: Remove the screws based on the numbering on the heat sink.
b Lift the heat sink assembly from the system board [2].
5 The component you are left with is the heat sink assembly.
36 Removing and installing components