Case fan problem maybe you can solve?


Mar 27, 2012
Hello, I just completed my first build which was exciting and stressful but im having a couple issues. One in which is my case fans working. I have three fans in my case. Two of the fans have molex connectors and the other a three pin. My mobo has one fan hook up which is a four pin lol (something I didnt check before buying). Ok so my case came with a molex cord with three molex connectors. Im able to connect the cord from psu to two fans then to motherboard but having that extra third open molex connection on the cord seems to be breaking the current. When I power on the beatutiful new comp the two fans kick on then off so thats what im thinking....the current is being broken or something by that extra third hook up...Got any ideas on what I should do?? and maybe on the three pin fan as well??


3 pin fan will work on a 4 pin header.

Can you describe the molex fan connection? often you'll see them get power from two wires thru a molex and then the rpm and the control wires (from the fan) go down to the motherboard. If thats the case then your motherbd has powered them down as its not warm enough to turn them on.


Apr 29, 2011
You are definitely connecting too many things together but you are not shorting our your motherboard. The fan connectors on your mother board and the molex connection are both designed to power your fans so by connecting the molex to your fans and then your fans to your motherboard you are tying together 2 sources of power.

Because you used all of the connections they way they were intended to be used (you just used too many of them) you tied all the pins on your mobo connector to their respective pins on the molex connector, ie. ground to ground, +12V to +12V. Because of this you did not short anything out. You are very lucky as many cases of incorrectly connecting things in your PC would fry it.

Your fans do not work because