t is well known that the Raspberry Pi 4 gets quite hot and reduces its processing speed if it has to work hard. In one of my Quickies, I tested the passive FLIRC case. In the comments, viewers pointed me to two Chinese cooling solutions and Cristopher Bartlett from Explaining computers tested a few others. Time for a new Quickie with a summary of all these coolers. And some ideas for optimizations. I am a proud Patreon of GreatScott!, Electroboom, Electronoobs, and others.