Had some trouble with this part. The thermal paste on mine was cold and very dry. Gave a loud POP when the first one came loose. The second one frightened me even more lol. And this was after removing the fan first and using a hairdryer on the top side of the heatsink, applying scattered heat to the front and back of the fins. Doubt I unseated the CPU and GPU... But we'll see when I get this monstrosity pieced back together!

The 4 black heatsink screws were easy to remove, but the 5 silver 9.5mm screws were a real pain. I had to carefully apply significant leverage to the top shield and rotate counter-clockwise, then clockwise, and repeat until they come loose. You really have to break them out of the threads holding them in.