> We use a Noctua cooling solution for both systems. For the 1st system, we mounted the heat sink centred. For the 2nd system, we followed Noctua's advice of mounting things offset towards what they claim to be the hotter side of the CPU. Below is a picture of the 2nd system without the heat sink which shows that offset. Note the brackets and their pins, those pins are where the heat sink's pressure gets centred. Also note how the thermal paste has been squeezed away from that part, but is quite thick towards the left.
> But note that the 1st failure happened with a more centred heat sink. We only made the off-centre mounting for the 2nd system as to minimise the risk of a repeated system failure.
I didn't write the article, I was just commenting because other users seemed to miss information that was written in it.
The picture with the thermal paste shows that paste was squeezed out from the entire perimeter of the CPU, so the cooler is making contact with the whole CPU. The paste is squeezed thinner near the lower side of the CPU because that's where the mounting pins are located, meaning that's where the mounting pressure is the strongest. The impression left by the thermal paste matches the diagram on Noctua's site ( https://noctua.at/pub/media/wysiwyg/offset/heat_cooler_base_... ).
Noctua lists the NH-U9S cooler as being compatible with the 9950X, and claims it has "medium turbo/overclocking headroom", see https://ncc.noctua.at/cpus/model/AMD-Ryzen-9-9950X-1831 . I'm not sure how they come up with their compatibility ratings, but I generally trust Noctua knows what they're doing when it comes to CPU cooling.
It's also important to note that the author only tried the offset mount after they had a CPU die when the cooler was mounted centered on the CPU.
Overall, I think it's unlikely that these failures can be blamed on poor cooling.
Probably there's less paste remaining on the south end of the CPU because that's where the mounting force is greatest.
If anything, there's too much paste remaining on the center/north end of the CPU. Paste exists simply to bridge the roughness of the two metal surfaces, too much paste is a bad sign.
My guess is that the MB was oriented vertically and that big heavy heat sink with the large lever arm pulled it away from the center and north side of the CPU.
IMO, the CPU is still responsible for managing its power usage to live a long life. The only effect of an imperfect thermal solution ought to be proportionally reduced performance.