[ollien]

> The small coolers used by them are not recommended by Noctua for 9950X

Noctua's CPU compatibility page lists the NH-U9s as "medium turbo/overclocking headroom" for the 9950X [0]. I don't think it's fair to suggest their cooler choice is the problem here.

[0] https://ncc.noctua.at/cpus/model/AMD-Ryzen-9-9950X-1831

[adrian_b]

That means pretty much "not recommended".

On the same page linked by you, Noctua explains that the green check mark means that with that cooler the CPU can run all-core intensive tasks, exactly like those used by the gmplib developers, only at the base clock, which is 4.3 GHz for 9950X, with turbo disabled in BIOS.

Only then the CPU might dissipate its nominal TDP of 170 W, instead of the 200 W that it dissipates with turbo enabled.

With "best turbo headroom", you can be certain that the CPU can run all-core intensive tasks with turbo enabled. Even if you do no overclocking, but you run all-core intensive tasks with turbo enabled, this is the kind of cooler that you need.

Noctua does not define what "medium headroom" means, but presumably it means that you can run with turbo enabled all-core tasks that have medium intensity, not maximum intensity.

There is no doubt that it is a mistake to choose such a cooler when you intend to run intensive multi-threaded computations. A better cooler, but not much bigger, like NH-U12A, has an almost double cooling capacity.

That said, there is also no doubt that AMD is guilty of at least having some bugs in their firmware or in failing to provide adequate documentation for the motherboard manufacturers that adapt the AMD firmware for their MBs.

[ollien]

It is important to remember that CPUs scale their turbo with thermals. It's not a matter of needing to turn turbo on and off