Originally Posted by mikupoiss
Originally Posted by EPiiKK
Okay, i think i solved this.
The 3 pin motherboard fan headers are not PWM? I put both of the fans to 4 pin headers, even tho the fans are 3 pin, and now i can control them fully. i thought the 3 pin headers were pwm too.
When i get my new case i'm gonna use spliters to put all my fans to the motherboard 4 pins!
I haven't seen a single 3-pin PWM. Can it even be made with the PWM spec? They all have 4 pins, so putting 4-pin fan onto 3-pin header doesn't report speed signal and is permapowered for high speed. Or something like that .P
No, 3-pin headers are not PWM. Some have no speed control at all.
4-pin headers are not all PWM either. Usually the only PWM headers on a motherboard are the CPU fan & CPU opt. 4-pin headers.
3-pin header pinout is Gnd, 12V, RPM signal. If header has speed control the 12V is variable voltage.
4-pin PWM header is Gnd, 12V, RPM signal, PWM signal. The PWM signal goes to PCB in fan that pulses the 12v powr to fan.
4-pin non-PWM header is Gnd, 12v, RPM. Reserved.
Some 4-pin headers can be both PWM or voltage control. Sometimes this has to be set in Bios, sometimes it's automatic.Edited by doyll - 3/16/14 at 4:31pm