Ryzen 7 5800X Cooling

Greetings,

What you are actually seeing here is a CPU IHS that is a bit concave while your cooler is machined to be more towards the flatter side. AMD CPU's are commonly concave while their coolers are slightly convex to offer a proper mating surface. Anyone that has ever used a stock AMD cooler and had the dread of pulling their cooler off without "breaking the seal" knows the fear of pulling their processor out of the socket due to how strong this mating surface vacuum can be.

The scratching you are seeing won't impact performance at all as thermal paste is designed to fill the micro-gaps and surface imperfections between the mating surfaces of your heatsink/AIO and CPU IHS, but you'll likely still experience higher thermals for a different reason entirely.

The Ryzen 7 5800X is a single CCD CPU, meaning there is only one core complex die on the CPU substrate:

The image above is a delidded 5600X (destroyed, but still illustrates my point). The die on the top left corner is the CCD die where your CPU cores reside. The larger die towards the bottom center is the IO die, where your memory controller and PCIe lanes reside. Your AIO cooler's fin array, the fin stack that defines the surface area and cooling potential of your AIO, is centralized, meaning the cooling is focused on the center of the CPU. Since most of the heat of your processor is generated on the corner, AIO's are often less efficient for cooling AMD's single CCD processors.

Der8auer, a renowned overclocked, managed to drop temperatures by 7C simply by creating a bracket to offset the location of his AIO back on Ryzen 3000: https://www.tomshardware.com/news/new-amd-ryzen-3000-overclocking-mounting-brackets-debut-for-just-dollar33

That said, the idle temps you are seeing are not a cause for concern. You are going to see higher idle temps on Ryzen because Ryzen's turbo algorithm is very aggressive during low-current "idle" workloads. When current drops below 20A, you typically see voltage values spike above 1.48-1.52V and turbo clocks of over 4.8ghz or more depending on power/thermal overhead. These will cause higher reported thermals during idle workloads, but should not be seen as a bad thing. As long as your processor is remaining cooler during your typical workloads (preferably under 80-85C for extended periods), you'll be fine.

I personally subscribe to the "pea sized dot" method and let the mounting pressure of my cooler perform the spreading. It's yet to fail me, and I've never seen any difference in performance vs manually spreading. My problem with manually spreading is my preferred thermal paste (Thermal Grizzly Kryonaut) is extremely viscous and difficult to spread, so attempting to spread it results in excess paste being wasted as it doesn't spread all that well with their included spatula.

As long as you have enough paste to cover the microscopic gaps of air, you'll be fine. With an AIO, you might need to press down on the cooler a bit after you tighten the mounting screws to make sure it spreads properly, as they typically don't have a lot of mounting pressure like your tower air coolers or custom water blocks would.

The IHS is actually nickel-plated copper, which might explain why the material felt a little different than anticipated. Glad to hear you were able to smooth those edges out, I didn't bother once I got my water block attached. So far, thermals are fine on my end.

The spikes in thermals sound normal, especially factoring in AMD's Precision Boost Overdrive and it's behavior with low-current, high-voltage at lower loads. Oddly enough, if you put your CPU under a heavy multi-core load, you'll likely see lower, more stable temps than what you'll see under a lighter, single-threaded load. At least that is what I've noticed with my 5950X.