IBM B50 - Manual (Page 159)

adhesive between the heatsink and CPU chip will be less likely to pull the
aluminum cap off the chip.
Replacement
1. If you are replacing a fansink 09P1126, first remove the paper pulltab to expose
the thermal grease underneath. Install the new fansink by hooking the side
opposite the finger tab and then pushing the finger tab side down until it locks
into position.
OR
If you are replacing a fansink 09P1129, remove the adhesive protective paper on
the bottom of the heatsink and place the fansink assembly into the metal bracket
on the system board assembly and secure the ends of the wire loop under the
edge of the metal bracket.
2. Plug the new fansink into the system board connector of the old fansink.
3. Reinstall the disk drive bracket assembly.
4. Reinstall the top cover.
5. Power on the system and run diagnostics.
Chapter 7. Removal and Replacement Procedures 7-15