4 Pin PWM to Dual PWM Fan Splitter Cable - Y Adapter for PC Case Fans - Connect Multiple Cooling Fans to Single Motherboard Header (Ideal for Gaming PCs, Workstations & Custom Builds)

I used this to add another fan to a desktop that did not have another fan connector on the motherboard. I used this to split the power going to the existing CPU fan in order to add a case fan. Working well, and was able to lower my temps about 20 degrees F. Just make sure you check to see if you need a 3-pin or 4-pin adapter. If you do a web search on "PWM", you'll understand what it is, and what the 4th pin is for.