Question Case fan 2 of em 3 pin, one 4 pin socket for the fans on mobo WHAT DO I DO

[808Ender]

Mobo: https://images-eu.ssl-images-amazon.com/images/I/D1HGiMP+v4S.pdf page 4 system fan is the socket.

Case: Rosewill FBM-X1 https://www.newegg.com/Product/Product.aspx?Item=N82E16811147262

 

[DavidM012]

plug them in one doth imagine. the 3 pin fans don't have the sense wire so doesn't have rpm control like a 4 pin true pwm fan. But they are both compatible with the pwm header. Only on the 3 pin fans the pwm circuit doesn't do anything because there isn't one.

 

[808Ender]

Doth imagine? Pwm header? is that sys fan on the mobo

 

[DavidM012]

Yes they are all pwm headers. They are identical as far as pwm function goes except the cpu header has halt on cpu fan error! built in to the bios that activates if no 3 or 4 pin fan is present and flags a warning on post, and prompts the user to enter the bios, rather than boot into windows. Which is a chance to shut down the system and rectify a faulty fan.

Some mobo's label them CHA Fan for chassis rather than sys fan for system fan. And you can have a CPU opt fan on some boards as well as a CPU fan header, so you get two so that coolers with two fans can go on their own headers.

Cpu and cpu opt are on the same circuit on my board, CHA fans 1-3 are on the same circuit and Cha 4 has it's own circuit so fans that are on the same circuit run at the setting specified in the bios.

You can switch off monitoring of the cpu fan header in the bios if for some reason you don't have anything that plugs into the cpu fan header to disable halt on cpu fan error! My pump is dc on another power supply and I have 6 pwm headers on my sabertooth hence I only plug a fan into the cpu header to stop the halt! flag.

You can get a 2 way splitter if you only have 1 spare header.