Small update:
After a reboot (first one since the BIOS update and the immediate reboot after that), the temp dropped significantly again! Probably the new BIOS kicked in somehow, and the plastic element is out, so now it's at least as low as at start. CPU at a constant 10-15% and the core temp is at 45 degrees. On idle it's 41-42 now 
Really, guys, remove that plastic piece of sh** from your X61!
Mark_Lenovo
didi_bxl,
Good job - glad you were involved here and able to help! Many of the forum readers might be concerned about having some small piece of plastic in their system that could be causing trouble.
Let's go over this to make sure that we are talking about the same thing....
When new fan / heat sink assemblies ship as a service part, they have small dots of the thermal transfer material applied in a little grid or matrix, to the chip contact side of the heatsink of the CPU and sometimes GPU, depending on the system. When the fan / heatsink is installed, these little spots flatten out, creating an even coverage and ensuring good heat transfer.
To protect these dots during shipment, a thin piece of clear plastic is applied. This is supposed to be removed during the installation.
Lenovo issued a servicer tip because we found that some servicers did not know to remove this when they installed the part and this plastic created an insulative barrier and inhibited the fan / heatsink from doing it's job.
The is a helpful bulletin and not a statement of an inherent defect. I want to be sure that we don't create the perception that customers have systems that are now running warm because of some mysterious plastic bits.
Was this plastic film you were referencing?
Best regards,
Mark
ThinkPads: S30, T43, X60t, X1, W700ds, IdeaPad Y710, IdeaCentre: A300, IdeaPad K1
Mark Hopkins
Program Manager, Lenovo Social Media (Services)
www.twitter.com/lenovoforums
www.facebook.com/lenovo
Hello Markt, and all other too, of course.
Yes, it's well the plastic included in a Lenovo's technical note. I've found it between the fan assembly and the chipset IC (not the CPU), on its original place. But don't forget I've replaced the fan assembly in the same issue. And of course, the plastic film removed comes from the heatsink. On the original fan assembly, this film is still on place. That's abnormal. Like this part is scrap, I'well verified, now, the film is again there.
If customers reading this forum, it's easy to understand this film is not only the source of this issue. The good and actual situation comes from 3 actions : the plastic film moved, replacement of the heatsink assembly and last BIOS set up. Each point giving a step between the 80°C and the 35°C.
Best regards.
Didier
