Im looking to buy an Asus motherboard. My budget would make me lean more towards the z97-A, but my decision will depend on the fan headers. I'm getting some mixed info and am hoping it can be clarified.
The manual for the Maximus VII Hero on page 1-43 has the fan header wiring diagrams
CPU_FAN - (GND,CPU FAN PWR, CPU FAN IN, CPU FAN PMW)
CPU_OPT - (GND,CPU FAN PWR, CPU FAN IN, CPU FAN PMW)
CHA_FAN1-4 (GND,CHA FAN PWR, CHA FAN IN, CHA FAN PMW)
All of them are wired the same. All PW.
The Manual for the Z97A on page
CPU_FAN - (GND,CPU FAN PWR, CPU FAN IN, CPU FAN PMW)
CPU_OPT - (GND,CPU FAN PWR, CPU FAN IN, CPU FAN PMW)
CHA_FAN1-4 (GND,CHA FAN PWR, CHA FAN IN, +5v)
So the CPU and CPU_FAN are the same on this model as the Maxius VII, but on the Z97-A the Chassis fan headers have a 5v for the 4th pin.
Based on the
ASUS Z97 Motherboards - Overview and Official Support Thread and multiple review sites "Full PWM and DC support is present on EVERY fan header across all ASUS Z97 motherboards from the Z97-A to Deluxe, ROG and of course the TUF series. " So this makes me believe they are all true PWM even though the wiring diagrams are different. And, on
http://www.asus.com/us/site/motherboards/z97/ it also says "PWM support on all fan headers".
Then in another post in these forums
Z97 Fan Headers in the 3rd post Praz says:
And as I stated above full control of both PWM and DC mode fans are supported on all fan headers for Z97. There really was no reason for the confusion with Z87. The fan header pinout specifications clearly showed pin 4 PWM control for the CPU fan header only. All other included fan header pinouts had pin 4 at 5V. Armed with this info one should know that PWM functionality was limited to the CPU fan header only.
Which would lead me to believe a 5v pin would indicate voltage control not PWM which would mean the z97-A is not PWM for the chassis headers.
I did some googling and some people have complained that the 4pin headers are not PWM but actualy voltage controlled.
So I phoned Asus customer service and the guy assured me all the headers were PWM on the z97-A and that I should feel confident in that. I wanted to believe him, but I still would like more proof, hopefully by someone who actually has or has tried PWM fans on the chassis headers.
So I posted in the other official asus forums
http://vip.asus.com/forum/ and got a response from a moderator.
Only the fan headers CPU_FAN and CPU_OPT are PWM (Pulse Width Modulation) controlled.
The four chassis fan headers CHA_FAN1-4 are not PWM controlled, but instead DC controlled. On these four headers are the PWM control line (pin 4) connected to +5V, which make the fans receive the full +12V on pin 1-2 (pin 1 is GND and pin 2 is +12V).
Pin 3 is the RPM sense line on both types of fans.
Whether you connect a DC controlled (3-pin fan) or a PWM controlled (4-pin fan) to the CHA_FAN1-4 headers, they will behave the same - running at a maximum of 12V.
The advantage with PWM controlled fans, is that they can run on lower RPM (minimum 20% of full speed) than DC controlled fans (minimum 70% of full speed).
PWM controlled fans always receive a pulse of +12V amplitude, but with varying width, while DC controlled fans receive a voltage from ? up to 12V. If a too low voltage would be allowed, the fan wouldn't start - or stop running.
He sounded very knowledgeable to me. Really confusing though. Is the info in
ASUS Z97 Motherboards - Overview and Official Support Thread misinformationÉ
If anyone has any further insight on this please it would be greatly appreciated. Thanks!
