Toshiba Magnia Z300 - Manual (Page 106)

Installing and Removing Hardware
CPU module 84
11 Lightly push the heat sink in the direction of the socket, and fix
it by engaging the clips with the upper and lower hooks of the
socket.
Attaching the heat sink
Fixing the clips
NOTE: Do not push the fin section of heat sink of the CPU
module. This may cause the deformation of the heat sink.
Push the CPU module until both ends of it become uniformly
horizontal on the right and left and confirm that it was inserted
completely.