Chosen Solution
Hello, I noticed that the small heatsink in the center of my logic board is loose. It’s kept in place with a double-L-shaped bracket that in is his turn is attached to 2 inverted U-brackets on the logic board. The bottom left inverted U-bracket on the logic board is broken/missing, so I can’t attach it back again.
(images found on iFixit, where the U-bracket is still in place)
But first things first: what chip is underneath this heatsink? This heatsink is probably loose since some time and the Mac still works like a charm. But if Apple designed that heatsink there, there must be a good reason. Update (04/14/2021) Thanks Dan. I don’t really use I/O on this Mac these days (except for the dual link DVI to my good old 30” Cinema Display), so that would explain why it is still in perfect shape. How to fix this? In order to hold the double L-bracket, the inverted U-brackets must be very solidly attached to the logic board (it takes a fair amount of force to fully spread the double L-bracket). Most probably, the logic board will need to be removed to repair the broken U-bracket. Could adhesive thermal tape solve this quicker?
Missing bracket bottom left
If I remember correctly this is the PCI bridge chip which the systems ports communicate with and onwards to the CPU. So as long as you don’t push your systems I/O which is served by this chip you likely won’t kill it. If you do then you’ll need a new logic board. To be safe, I would get it fixed if you are expecting to use this system for another 3 or so years.
