I learned last year while preparing to replace B0-stepping Atom C2000s the "paste" typically used in enterprise-class non-upgradable chips aren't thermal paste. Some are made of thermal plastic that melts and forms a bond between the chip and heatsink during first use power up. These TIMs have thermal conductivity of ~7.5 W/mK per their datasheet. https://www.mouser.com/datasheet/2/987/THR_DS_Tpcm_7000_Data_Sheet_03172023-3194660.pdf. My guess is these TIMs have more lasting properties than typical thermal paste.
I'm always concerned that improperly removing the heatsinks would delid the chip from its package. I have read some vendors use thermal glue instead of what I've linked above. Luckily by twisting the heatink and not force lifting I was able to remove the CPUs without incident. It would have been fine if the chips were damaged because they would have been tossed anyway due to the LPC bug.
I'm always concerned that improperly removing the heatsinks would delid the chip from its package. I have read some vendors use thermal glue instead of what I've linked above. Luckily by twisting the heatink and not force lifting I was able to remove the CPUs without incident. It would have been fine if the chips were damaged because they would have been tossed anyway due to the LPC bug.