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Arctic Cooling PWM confusion

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July 6, 2011 2:20:19 PM

Hi, I'm planning to buy 2 case fans from Arctic Cooling, one 92mm, one 120mm, both F PWM series.
Specifically these two:
http://www.arctic.ac/en/p/cooling/case-fans/73/arctic-f...
http://www.arctic.ac/en/p/cooling/case-fans/73/arctic-f...

I read a PWM is sent to the CPU through BIOS but I am unsure as to how it achieves this. How can I know if my motherboard supports PWM Sharing Technology (PST)?
My Asrock H61M-VS motherbaord uses UEFI and has hardware temperature monitoring with the option of automatic setting or full on fan control.
I'm really confused with this PWM thing...
a b K Overclocking
July 6, 2011 2:34:54 PM

PWM Basically controls the fan speed. If the system heats up, the computers knows to speed the fans up to cool them down. This is how the CPU fan works.

With case fans you can either connect them to the PSU directly via 4pin Molex and have them running as fast as possible constantly with no way to slow them down or you can connect 3pin fans to motherboard fan headers which in this fans case with PWM means they will run as fast as they need to run. This is good since it will create less noise and use less power.
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July 6, 2011 2:45:17 PM

Ok, but how do I now if my motherboard support this technology? The manual doesn't say.
Or maybe this is a Arctic Cooling patented thing that will support all motherboards with 4-pin/3-pin fan sockets?
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July 7, 2011 8:57:13 AM

AdrianPerry said:
With case fans you can either connect them to the PSU directly via 4pin Molex and have them running as fast as possible constantly with no way to slow them down or you can connect 3pin fans to motherboard fan headers which in this fans case with PWM means they will run as fast as they need to run. This is good since it will create less noise and use less power.


Actually PWM fans have to be connected to the *4-pin* header for auto control. The 3-pin headers will monitor fan speed but not change it See my reply to OP.
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July 7, 2011 9:26:36 AM

dragonic2020 said:
Ok, but how do I now if my motherboard support this technology? The manual doesn't say.
Or maybe this is a Arctic Cooling patented thing that will support all motherboards with 4-pin/3-pin fan sockets?


Actually your manual has this information (I just bought this AC fan and have an AMD Asrock MB). Page 25 shows the fan headers and explains that the 4 pin header must be used for PWM control (it doesn't use the word "PWM"). Page 48 shows you where in the UEFI the fan control settings are located.

BTW, for sw such as HW Monitor to register the rpm of the fan, both the 4 pin and 3 pin connectors must be connected. The 4 pin controls the speed but doesn't report it and the 3 pin vice versa. You can also plug the AC 3 pin connector into the 4 pin daisy chain socket on the fan's cable which will also result in the speed being reported. Although I find that whatever sw I use the CPU and Fan speeds are reported sporadically.

It's a very nice quiet fan but the supplied screws didn't work in my Antec Sonata case. I had to use some silicone fan mounts I had lying around.
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Best solution

July 7, 2011 9:30:18 AM

dragonic2020 said:
Ok, but how do I now if my motherboard support this technology? The manual doesn't say.
Or maybe this is a Arctic Cooling patented thing that will support all motherboards with 4-pin/3-pin fan sockets?


Actually your manual has this information (I just bought this AC fan and have an AMD Asrock MB). Page 25 shows the fan headers and explains that the 4 pin header must be used for PWM control (it doesn't use the word "PWM"). Page 48 shows you where in the UEFI the fan control settings are located.

If you want both fans controlled by PWM one must be connected to the 4 pin chassis fan header on the MB and the other must be plugged into the 4 pin socket on the AC fan cable.

It's a very nice quiet fan but the supplied screws didn't work in my Antec Sonata case. I had to use some silicone fan mounts I had lying around.
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a c 197 K Overclocking
July 7, 2011 9:44:12 AM

channeledbymodem said:

BTW, for sw such as HW Monitor to register the rpm of the fan, both the 4 pin and 3 pin connectors must be connected. The 4 pin controls the speed but doesn't report it and the 3 pin vice versa.

Not true. The 4 wires provide both monitoring and control.

You can also plug a three wire fan into the 4 pin CPU fan header. You keep the monitoring feature (no missing fan BIOS errors), but you lose the speed control function.
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July 7, 2011 9:57:28 AM

For whatever reason, plugging this particular AC fan into the 4 pin header and leaving the 3 pin unattached to either a second 3 pin header on the MB or the daisy chain socket on the AC cable results in no monitoring. I have the same fan and had the same problem. A Google search provided the solution of plugging the 3 pin cable into the socket.

How other fans that only have a single 4 pin connector and no daisy chain socket may work I don't know but my description is accurate for this fan.
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July 8, 2011 6:58:04 PM

Best answer selected by dragonic2020.
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July 8, 2011 7:01:50 PM

Thanks ppl.

I just bought both fans pictured in my original post.
I followed the instructions that came with the fans and it worked fine.
My board actually has 2 4-pin fan connectors. 1 for the CPU fan and 1 for the rear fan.
I put the 120mm fan in the front and the 92mm in the back.

They run really quiet. The loudest thing now is either my GPU fan or CPU fan.

Guess it's time to upgrade the CPU fan + heatsink!
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