What's the difference between:
1. +12V (CPU FUN - 2 pin) and Speed Control (SYS Fun 1, 3 - 2 pin)
2. Speed Control (CPU FUN, SYS FUN 2 - 4 pin) and VCC (SYS FUN 1, 2 - 4 pin)
There are about
5 variants of the GA-Z170X-XXX - I'll just pick one.
GA-170X-UD5
Based on my understanding of this.
1. If you use a 2 pin FAN on a 3-4 pin header, the fan will run at full speed since it is receiving constant 12v. Speed control is not possible.
2. PWM vs. VCC - 12v vs. 5v.. Poor non standard implementation. MB manufacturers have not done a good job agreeing on a standard for FAN control. Some headers use Pulse Width Modulation, while others use VCC. Some say its called variable voltage, some refer to it as collector control. The theory is you are suppose to be able to use splitters on the SYS_FAN 1/2/3 headers but not on the CPU_FAN header as the latter only has the ability to control the speed of one fan.
I'm using 3 PIN fans on my SYS_FAN headers without problems. All run at variable RPM depending on heat/load.
