.... well, those of you who are old enough remember the rest of the old slogan. Over the weekend I pulled out my Quad G5 to play around a little and to make a couple of tweaks. As I was moving it, I dropped it with one hand and one end of it klunked onto the floor (fortunately not too hard) about 8 inches. I figured all was probably OK, but when I went to start it, it failed with the light on for CPU A overheating. I stopped, checked a few things and tried again. Same thing. Eventually I pulled out most of the RAM (from 16 GB down to 4 GB, just two matched sticks) and got it to boot up. Then I went to reduced performance mode and that allowed my trusty Quad to limp along, with CPU A temps in the low 80s with spikes into the 90s, and CPU B in the 40s and low 50s. OK, turn that sucker off before CPU A completely fries! So I figured that *probably*, that bump caused something to go awry. I decided to go with the easiest fix, the thermal paste, figuring that maybe the bump caused the last adhering paste to loosen up and stop working. (It is a single pump unit and one CPU was not overheating so I decided the LCS was not the likely source of the problem.) So today, I took the plunge and redid the thermal paste. This was the first time I have done it on the G5; I have removed and swapped out the complete CPU/heatsink assembly but never the thermal paste. The teardown to remove the entire assembly is well documented. The part about removing the CPU module for repasting, not so much. I eventually figured out that I needed to remove 10 hex screws on each CPU and it came right out. Armed with some rubbing alcohol to remove the old paste -- which looked almost nonexistent -- and reapplying new paste (I went with Noctua NT-H1) I reversed all the steps to rebuild. It was flaky getting it to restart. But I found that I really had to tighten the CPU/heatsink assembly really well or else the motherboard would complain it could not see one or both CPUs. But finally it started up. Now it still needs time to fully cure, but I ran it for a few minutes and here are the temps now (see attached). In particular, A and B are almost identical. So I feel pretty confident that the problem is corrected and the ancient (probably original) thermal paste was the issue. It should be even better, I hope, in the days and weeks to come as the paste cures.