Adding external fans

harshil123

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Feb 1, 2012
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Hi, I've recently got some spare time and money to sort out my extremely loud computer. I currently have a ;

Antec Three Hundred Mid Tower ATX Computer Case

The case has the standard bacvk and top exhaust fan. On top of this I have installed two, 3 pin front fans. On top of this I changed the stock CPU heatsink. Now here's my problem;

My Motherboards is Asus p7p55D-ELX. Most of the noise from the fans come from the exhaust and side fan, which are both running on the highest setting. Now my motherboard supports fan control through a software. However the stock exhaust and side fans don't have a 3 pin or 4 pin connection which allows them to be controlled by the motherboard. So I'm looking to replace them with 2* Noctua NF-F12PWM's.

The following image is taken from my motherboard's user guide:



My CPU heatsink is currently plugged into the CPU_FAN port. My two front fans are plugged into CHA_FAN1 and CHA_FAN2. The issue is if I replaced the two noisey fans (top and back), the feature that allows them to be controlled via the motherboard only works in the CPU_FAN, CHA_FAN1, and CHA_FAN2 ports. As it shows on the bottom of the picture. I need some way of keeping my front two fans whilst also being able to plug in my new noctua fans into places where they can be controlled by the motherboard.

Sorry if this is a long post or confusing, I tried to keep it as simple as possible...

Thanks in advance!
 

byza

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Only 4 pin fans connectors support PWM. You might be better served getting a fan controller.
Fan Controller: NZXT Sentry Mesh Fan Controller ($21.24 @ Amazon)
Fan Controller: NZXT SENTRY 3 Fan Controller ($30.99 @ SuperBiiz)

That is to say that only your CPU and CHA_1 fans have PWM, but since your front fans only have 3 pins, they don't have PWM. By getting a fan controller, you will be able to adjust the speed of all your fans, which seems like the best option to me.
 

byza

Honorable
Yes, but if you're getting a voltage fan controller, your better off getting voltage controlled fans. Most companies will offer the same fans in voltage control and PWM, but due to the more complex motor of PWM fans they are more expensive. The Noctua FLX fans are designed for voltage control.
 

harshil123

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I'm a bit confused I thought non PWM fans are voltage fans. If I buy the Noctua FLX which it says is PWM then how can it be designed for voltage control?

Thanks for your help bdw!
 

byza

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Voltage control has 3 standard voltages: 5v, 7v and 12v.
In reality all fans can be voltage controlled, but fans not all fans are actually made to run at less than 12v, and as such may stall at lower voltages. So in the case of fans that are not made to run at lower than 12v, I don't really consider these to be voltage controlled.
You can often tell the difference because a fan that supports voltage control will have 3 different RPM's or a high and low speed but no PWM in the title, PWM usually says PWM and non voltage controlled fans just have one speed.
With Noctua, the PWM is PWM, the FLX is voltage controlled at 5v, 7v and 12v, and the ULN is non-voltage controlled (or actually has only 2 levels of voltage control as i believe the Noctua low noise and ultra low noise adaptors are actually voltage controllers).
I have a Noctua ULN fan connected to a voltage fan controller and it will work at 7v and 12v, but at 5v it needs to be flick started.
 

harshil123

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One final thing, if I was to get a fan controller would you have to adjust it manually to be lower speeds when just on idle then turn the dials again to put the fans on high when gaming, or can it be done automatically?
 

byza

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It depends which fan controller you buy. Some have automatic functions, some are fully manual.

If you buy a 3-pin fan controller, buy 3-pin fans. If you pair 4 pin fans with a 3 pin controller, you can reduce the fans life.
 

harshil123

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Firstly, I'd like to say a huge thanks to you for your help. You've been so helpful!. Secondly, I hope this is my last post before I can close this thread- if my front meshing of my case where the fan controller will go is 6 inches will that be enough room because from the pictures it seems massive.