The thing gets very hot under constant CPU load. I have therefore glued an 18x18mm heat sink onto the CPU. I use the red and white original housing from the starter kit. With the lid closed, the temperature still rises to around 86°C; if I leave the lid off, it's just under 70°C. I tested the official Raspberry Pi case fan (from Pi-Shop.ch, not available at Digitec). I removed it again because it was so loud. I was thinking about a metal case, but because of WiFi I don't want to install a faraday cage in the form of a metal case. How do you cool your Pi4? Do you know of a solution where you don't have to keep the case open all the time, but is still quiet enough so that the thing doesn't disturb you?