HP ProLiant DL560 Gen11 User Manual page 156

d. Set the anti-tilt wires to the locked position.
e. Use a T-30 Torx screwdriver to tighten one pair of diagonally opposite heatsink screws (callouts 1 to 2), and then tighten the other
pair of heatsink screws (callouts 3 to 4).
Standard heatsink
HPE ProLiant DL560 Gen11 Server User Guide 156