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ASUS Z87 - Plus PWM fan confusion

Last response: in Motherboards
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May 8, 2014 12:05:07 AM

Hello,

I am upgrading the fans on my system and I was wondering what the benefit of PWM is. I was also wondering if I would be able to connect 5 PWM fans to my MoBo. I have an Asus Z87-Plus and was looking to put 2 Cougar Vortex 140mm 119.8 CFM as front intake 2 Cougar Vortex 140mm 119.8 CFM on my Kraken X60 on the top as intake and 1 Cougar Vortex 140mm 119.8 CFM in the rear as exhaust. I have a H440 case.

Thanks
May 8, 2014 12:20:28 AM

If you have a look at page 1-38 in the user manual for your mobo: http://dlcdnet.asus.com/pub/ASUS/mb/LGA1150/Z87-PLUS/E7...
you can see that while the CPU_FAN and CPU_OPT headers have a PWM signal on the fourth pin (both controlled by the cpu temperature, and controllable in software sollutions such as Fan Xpert2), all the other 4-pin fan headers have a constant +5V signal on the fourth pin, and control the fan over voltage control. So if you wish to use these for chassis fans, you will waste your money if you buy pwm controlled fans.

If you want to control all fans over the cpu temperature, you can use a pwm fan header splitter (e.g. http://www.swiftech.com/8-WayPWMsplitter.aspx), but you will not be able to control the chassis fans independently.

Edit: Forgot to mention: You can control PWM fans over voltage control, but voltage control will control any fan. As long as the voltage control is of good quality, it is exactly as good as pwm. But with PWM you are able to split control signals over more than two fans (with the kind of splitter as given above). As fan headers usually do not support more then two fans, this is not possible with voltage control.

I also think that the standard fans following the H440 are just as good as the fans you mention, but you just might like the looks of the Cougars better ;) 
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May 8, 2014 12:37:14 AM

Thanks paulbatzing, one more question. With the Kraken X60 it comes with stock pwm fans but if I understand what your saying correctly I cannot utilize them with my MoBo? Also the Cougar fans are quieter and have better CFM (70.5-119.8) compared to stock fans (50). They are also orange which is my theme. But if my MoBo cannot support PWM then I might as well get the cheaper non PWM ones.
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May 8, 2014 12:48:12 AM

You will connect the Kraken to the cpu-fan headers I guess? There are two PWM controlled cpu headers on your board, CPU_FAN and CPU_OPT. You need to connect a fan to CPU_FAN (or the bios will think that you do not cool your CPU and give you warnings), and since CPU_OPT is controlled by exactly the same PWM signal as CPU_FAN it makes sense to connect the second of your fans to this header.

For the other fans you have two possibilities: Either use the cpu PWM signal for all fans by using a splitter as mentioned above (which might not be what you want, as the chassis fans should power up if the case gets hot, not the cpu imho), or use the CHA_FAN headers for the other fans. If you use the CHA_FAN, you will be able to control the RPM of the fans no matter wether they are PWM or not, so going for (more expensive) pwm fans is unnessecary.

One final thing to consider: I believe asus lets you set a minimum load of 40% on the CHA fans and a minimum load of 20% on the cpu fans, so the minimum RPM of the fans might not be achievable on the cha headers.
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May 8, 2014 12:51:21 AM

Thanks :)  While I have you attention, would it be better to get airflow or static pressure fans? I know the H440 has limited air intake so I was thinking static pressure for intakes but I am not sure.
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May 8, 2014 12:55:13 AM

I do not own the H440, but usually aiflow fans perform better. Static pressure fans work best when they have something to push the air through. The difference should be small for intake, and airflow fans are usually cheaper, so I would go for airflow :) 

please select a sollution if the problem has been solved :) 
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