Your motherboard's tiny fan header can do way more than cool your CPU

Fan headers on motherboards serve more purposes than just powering a CPU cooler. They use 4-pin connectors (ground, power, tach, PWM) and are typically rated at 12V/1A, though some headers support 2A or 3A for AIOs and pumps. Beyond CPU fans, they can safely power case fans, AIO pumps, standalone water cooling pumps, and fan hubs. Using a powered fan hub is recommended to avoid overloading headers. Custom water cooling pump speed can be controlled via PWM signal through a fan header, though the pump draws power from the PSU directly. RGB/ARGB strips should never be connected to fan headers as this risks motherboard damage. Connecting an Arduino to read the PWM signal is possible but powering it from the 12V fan header is inadvisable.