Or, instead of jury rigging some sort of concoction to keep a 95W CPU cool with a cooling system that was designed for 65W CPUs you could instead just get an iMac with a 65W CPU and not worry about temperatures and fan noise at all. I dare to say that most users are not going to notice the difference between the 65W i5-8500 or i5-8600 and the 95W i5-9600K. Yes, it might be a split second slower here and there but nothing to write home about. In return, it should remain MUCH cooler and quieter. Case in point: my 2017 base model (3.4 GHz i5) never exceeds 70°C under full load, and I have yet to witness the fan rev up above its 1,200 rpm base line.
The i5-9900K is a different story since it has two additional cores. Plus it is also the only one available with the optional Vega 48 GPU. Why? Because Apple said so.