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0 pointsndiddy7mo ago0 comments

This is per design. On AM5 processors, there's a hotspot on the lower half of the processor where the dies that contain the CPU cores are located. Noctua recommends that AM5 users mount their coolers shifted towards the lower side of the processor for optimal cooling performance, see https://noctua.at/en/offset-am5-mounting-technical-backgroun... . You may have missed the paragraph in the article that explicitly points this out:

> 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.

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nolok7mo ago

While it is noctua advice, I don't think AMD supports that view, so it would seem correct to at least test the cpu the way the vendor recommends before making conclusions

ndiddyOP7mo ago

You may have missed the part in the article that says that they only switched to offset mounting after their first Ryzen 9950X died when the cooler was mounted centered.

> 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.

dukezzz7mo ago

Noctua recommends mounting their cooler so that the center is shifted toward the lower part of the CPU. From your picture with the thermal paste, it’s clear that your cooler is only making contact with about two-thirds of the CPU, meaning you mounted it incorrectly. The cooler’s contact area must always cover the entire CPU; otherwise, you reduce heat transfer capacity. On top of that, you’re already using an undersized cooler for this CPU. I think you don’t understand the basics of thermodynamics.

ndiddyOP7mo ago

Welcome to Hacker News! I'm glad my comment encouraged you to join the site.

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.

spoaceman77776mo ago

i'm not sure what image you're looking at, but the picture in question here most certainly shows a CPU that did not have a properly mounted heatsync (to a very severe degree)

j / k navigate · click thread line to collapse

0 pointsndiddy7mo ago0 comments

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nolok7mo ago

While it is noctua advice, I don't think AMD supports that view, so it would seem correct to at least test the cpu the way the vendor recommends before making conclusions

ndiddyOP7mo ago

You may have missed the part in the article that says that they only switched to offset mounting after their first Ryzen 9950X died when the cooler was mounted centered.

> 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.

dukezzz7mo ago

ndiddyOP7mo ago

Welcome to Hacker News! I'm glad my comment encouraged you to join the site.

I didn't write the article, I was just commenting because other users seemed to miss information that was written in it.

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.

spoaceman77776mo ago

i'm not sure what image you're looking at, but the picture in question here most certainly shows a CPU that did not have a properly mounted heatsync (to a very severe degree)

j / k navigate · click thread line to collapse