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Will my 1200 rpm fans spin at max speed if connected with ASUS Maximus VI Hero?

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March 20, 2014 5:02:15 PM

Hey guys I am in the process of building a gaming PC. I have 2 intake and 1 exhaust Noctua 1200 RPM fans (NH-A14 FLX) that I have the option to either connect to my Fractal Define R4 case fan controller or my Maximus VI Hero motherboard. If I connect these three (3-pin) fans to the motherboard will they always spin at maximum 1200 RPM?

I am debating using the fan controller (5V, 7V, 12V)

Any help or suggestions will be much appreciated!
March 20, 2014 8:14:58 PM

The reason why I am asking is because I am unsure if I can control the fan speed while having 3-pin fans connected to the Maximus VI Hero MB.
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March 20, 2014 9:15:01 PM

Unfortunately, the mobo manual does not answer this question, but hints that the answer is "no".

In the manual Section 3.7 Monitor (in BIOS Setup), on p. 3-40 it says that the CPU Q-Fan Control settings include "Advance Mode" which makes the CPU _Fan port behave as a 3-pin fan port. But on the next page where the three CHA_FAN port settings are detailed, there is no such setting. It says that "Enabled" will turn on the Chassis Q-Fan Control, and implies that it is only able to function as a 4-pin fan port. If you connect a 3-pin fan to a 4-pin port, the fan will always run at full speed because it cannot use the PWM signal from the 4th pin.

In Chapter 4, page 4-11, it tells you how the Fan Expert 2 (software on the support CD) works, but does not address your specific question. Moreover, it is vague by saying that the details of the software you get depends on the mobo you buy, and on what they decide to change as time goes on.

Bottom line is, if you really want to use the mobo's automatic control feature for the chassis fans, you most certainly CAN do that IF you buy 4-pin fans. BUT since you are buying 3-pin ones, the manual suggests it won't work. You most certainly can try it that way, and it just might work even though the manual does not say that clearly. If it does not work, there's no harm done. You will get more cooling that you need (all fans at full speed), but no automatic control. Then you can move the fan connectors to the case's manual control system and use that.
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May 8, 2014 6:25:50 PM

I have a maximus hero vi and until today had three 3-pin fans connected to it. While looking at stats on CPUID monitor, it showed the fans were correctly being controlled by the motherboard. They did not run at full speed all the time. The strange thing is i just upgraded to some Noctua 4-pins and they seem to pretty much stay full speed... I cant remember whether I changed something in the bios or not (i need to mess with it later when i have time), but as an answer to your question, yes the mobo will control 3pin fans based on temperatures and the Q-Fan control settings.
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May 8, 2014 7:45:00 PM

Burrmanchu, that is good info from someone who knows the hardware because you use it! As I said, the manual indicates that only the CPU fan port can be set to operate as either a 3-pin or a 4-pin port, and the chassis fan port capabilities are not clear.

You comment on the 4-pin fans is odd, though. What should happen if you connect a 4-pin fan to a 3-pin port is that the port DOES control it just as it would a 3-pin unit. It does that because it sends out varying voltage to the +VDC line, and no signal to the PWM line, so the 4-pin fan operates at "full voltage" - that is, at whatever voltage it is supplied by the port. On the other hand, if the port somehow is changed to operate as a true 4-pin port, then the 4-pin fan also should be completely controlled by the port.
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