Review on 🌀 ANVISION 2-Pack 40mm x 10mm DC 5V USB Brushless Cooling Fan with Dual Ball Bearing Design - YDM4010B05 by David Robinson

One of the most common problems with using the Raspberry Pi is that the fan stays on even when the Pi is safely "off". Since most fans are connected to the 5V GPIO pin, the fan still runs on power and it is not possible to control it through these pins. One option is to use a moffet PCB to break the power without damaging the fan, but then you may have to solder which may cause problems for some people. Another option is to use an NPN transistor to control the fan directly from another GPIO. This is actually a good way to deal with this, as you can program how you want the fan to run, when to activate it based on when the Pi is powered on, or even based on the current temperature. But you have to plug the adapter in properly and do some coding, and that can scare some people. Of course, the easiest way to deal with a fan is to use a USB fan. When the Pi is powered on, it basically applies power to the USB port to turn on the fan. When the Pi is turned off, the power from the USB port is cut off, causing the fan to turn off. No coding, soldering or transistors required. Of course you have to do without the USB port, but for me it's worth it. I use this fan to restore my gaming console and it's perfect for what I need. It runs quietly and keeps the Pi temperature at 45 degrees at all times. Would definitely recommend to anyone doing Raspberry Pi projects.