The case is a Fractal Design Meshify C tower-case which seems a bit snugg i was suggested that BeQuiet Dark Rock Pro 4 before. Can it still keep this cpu cool with that RPM that it has?
Fractal Design Meshify C is a perfect case for airflow and my personal recommendation to many.
However, airflow still depends on your case fan placements. The most efficient placement is 2x 140mm/3x 120mm intakes and one 120mm or 140mm rear exhaust. No fans on top. Cool air from the outside goes into the CPU cooler, and hot air from the CPU/GPU leaves out the back. Streamlined front to back airflow.
I personally use 2x 140mm intakes and 1x 140mm exhaust, quieter and moves the same amount of air as 3x 120mm intakes on the front.
Anyhow, the Dark Rock Pro 4 can definitely keep a 3900X cool, it's a high end CPU cooler which is on par with the Noctua NH-D15/NH-D15S. I am recommending against it because of the installation, and the fan clips which are a nightmare to remove.
I am recommending the Noctua coolers mentioned above because they have an extended warranty of 6 years compared to the Dark Rock Pro 4's 3 years (which means that Noctua sends you fan replacements free of charge if one of them happens to die out, which is extremely rare with Noctua fans), Noctua provides you with free mounting kit upgrades in case you want to keep using the cooler on another motherboard, and the coolers come with an entire tube of high-end NT-H1 thermal paste, compared to the measly amount of paste the Dark Rock Pro 4 gives you.
But, this is just a recommendation. You can still go with the Dark Rock Pro 4 if you want. If you DO go with any of the Noctua coolers, be sure to check motherboard compatibility and case clearance on Noctua's website.
Lastly, RPM barely matters on a fan. What matters is the static pressure (if mounted on a CPU cooler heatsink) and the CFM (amount of air it moves). My Noctua fans are so efficient I don't even need to bring them past 1000 RPM even under load.