My downstairs TV Raspberry Pi 4 started showing a little thermometer icon in the upper right corner while I was streaming some hi-def video. Turns out it was overheating, or close to it. I didn’t put the fan in since I put heatsinks on the processor and two other chips and didn’t think it was necessary. But I suppose under heavy use, especially streaming video, heat gets to be a problem. I snapped the fan in, plugged it in to the 5V on the header and the temperature quickly dropped 40F. Now I wonder if my WiFi problems on my desktop were heat related. Both my Raspberry Pi 4s are now on ethernet, so I’ve stopped fighting the wifi battle.