I haven´t had that cooler nor the case, but I have some experience with these ryzens. Take in mind that the ryzen processor are difficulkt to cool because the placement of the chiplet. I don´t know if it´s possible, but try to rotate the heatsink 90 degrees to see if heatpipes work better that way. In my experience having owned a 3700x and now a 3950x it´s not more difficult to cool the latter over the former, because it´s difficult for the heatsink to extract the heat from one of the sides of the IHS instead of the center, so heatsinks probably can´t work properly with ryzen cpus specially with those that only have one chiplet.
Der8auer has design a braket to use with coolers so one can move ir around the socket a bit and work around this problem, take a look at the video. It´s not officially suported for itx motherboards, so maybe it´s not the solution.
Something I can tell you is that I had similar temp problems with my 3700x and a black ridge on a kolink rocket, the fan was going up and down like crazy with no apparent reason, and cooling was not that good, I ended up with a 12 cm fan on It got better after I lapped the processor, but anyway, I found it difficult to cool specially comparing it to the 3950x.
Another bit of data. With my RL on a Ncase M1, and the 3700x concuming 110-120 w it could easily go up to 90 degrees, but with the same RL and the 3950x consuming 200-210w it stays at 70 something. This is why I think the problem is the position of the chiplet, and because of that the current gen of heatsinks is not able to work to its full potential.
