120mm fan PWM or not?

[kontrol]

I have an HAF922 case and 2 of my fan are dead (Been more than a year now, I'm lazy).

After many reviews and setted my requirements in term of cooling and noise I stopped my choice on Corsair SP120 Performance and Corsair AF120 Performance (Need 1 SP and 2 AF).

About to make the order I notice there's the PWM version of what looks to be the same fan. Since I'm no master of cooling I wanted to know if there's a difference between both other than one has 1 more pin for the PWM.

Do my cable in my case support the PWM? Is there a difference in efficiency with the PWM version? Any trade-off? If I don't have a fan controller is it worth using the PWM?

 

[DonkeyOatie]

PWM allows for speed control from the BIOS/Motherboard. What motherboard do you have, and how many PWM fan headers does it have?

 

[Rogue Leader]

PWM fans would need PWM plugs on your motherboard, you need to check your manual if you have 4pin PWM plugs. Usually Motherboards only have 1 for the CPU fan. So PWM control is handled by a fan controller.

Otherwise the fans are identical. If you don't have a fan controller don't bother.

 

[RedJaron]

The PWM pretty much is the same fan, it simply has a 4-pin plug instead of 3-pin. That fourth cable is used to control the fan speed from the mboard.

Simplest answer is that if the fans you're replacing have 4-pin plugs, then getting PWM replacement fans makes them plug'n'play. If your dead fans are regular 3-pin fans, then getting PWM fans probably doesn't make sense unless you want to change things around.

If you want a more detailed explanation about PWM and fan speed control, I can do that.

 

[kontrol]

If I don't have a fan controller it's up to my mobo to provide 3/4 pins cable? Is this correct? (My mobo is a P6X58D-E. I tried to lookup the info on the cables but couldn't find it. I'm curious to know how many cable of 3/4 pins I have).

Also is it possible to plug a PWM fan with a 3pin cable? And if so would it do the same thing as using a non-pwm fan with a 3pin cable?

And if I have 4pins cable, can I plug a non PWM fan?

Sorry for the many question I'm trying to understand! Also depending on my result with my cooling expiriment, I might be tempted to buy a fan controller to play with speed to have a quiet mode (when not playing) and a performance mode.

 

[Rogue Leader]

Your motherboard won't come with cables the only fan cables come attached to the fan permanently. The board has 3 or 4 pin fan headers. 99% of the time it only has 1 4 pin header for the CPU fan, the rest are 3 pin. You can plug a 4 pin fan into a 3 pin header you just lose the control ability. You can also plug a 3 pin fan into a 4 pain header, same thing no control ability (obviously).

Heres your motherboard:

https://www.asus.com/Motherboards/P6X58DE/

In there you can find the manual which will tell you how many 3 pin plugs you have. Or if you click on specs it says there is 1 4 pin for the CPU and 2 3pins for fans.

You can also buy 3 pin fan splitter wires:
http://smile.amazon.com/StarTech-com-TX3-Power-Splitter-Cable/dp/B000E9ZQBU/ref=sr_1_2?ie=UTF8&qid=1443554836&sr=8-2&keywords=3+pin+fan+splitter

To run 2 fans off 1 3 pin header.

 

[kontrol]

It's becoming more clear!

I found out the specs tab for my mobo, which I didn't see at first. I have 1x CPU fan connector, 1x 4pin connector, 2x 3pin connector. 1 power fan connector. What is a power fan?

A non-PWM fan should run at 100% speed I guess? What about a PWM fan not connected to a 4 pin header? will it run at 100% or is it going to run at 50%?

 

[DonkeyOatie]

A PWM fan connected to a three pin header, will run at it's full power.

The CPU fan is likely four pin PWM so the PSU can get what it needs. I use cheaper motherboards, and all of my cases use 3 pin fans, some with Y splitters, with no problem. Most of my fans are Corsair AF or SP, and some are Quiets.

 

[kontrol]

So if I intend to move to a fan controller in the future and the PWM fan are the same price (I think they were in special so cheaper) there's no reason not to take the PWM in my scenario?

 

[Rogue Leader]

Sorry I read your specs wrong, so you have 1 CPU fan which is PWM as well as 1 4 pin PWM connector for a chassis fan which is good. So you can plug in a 4 pin PWM fan in addition to 3 3 pin fans. 1 of those 3 pin fans PWR_FAN is on 100% all the time, the other 2 3 pins works with the ASUS fan xpert feature, I've never used it but it may allow some sort of speed control through voltage. I wouldn't count on this feature so I'd assume they are 100% all the time.

 

[Rogue Leader]

So if I intend to move to a fan controller in the future and the PWM fan are the same price (I think they were in special so cheaper) there's no reason not to take the PWM in my scenario?

right

 

[RedJaron]

Your particular board has two 4-pin headers and three 3-pin headers.

And yes, you can mix/match fans and headers. Plugging a 4-pin fan into a 3-pin header just means the fan can't work in PWM mode. You can also plug a 3-pin fan into a 4-pin header. However if you do this, that fan will likely be set to full speed. This is because the mboard will try to control speed using the fourth PWM wire that the fan doesn't have. Read below to understand why.

Fan speed control is handled in two primary ways: you can either change the voltage to the fan or change how long the voltage is turned on. The first method is the oldest. Using resistor wires or fiddling with the 12V, 3.3V, and 5V lines on the mboard let you set a fan to run at 12V, 8.3V, 7V, 5V, or 3.3V.

However that was a static speed and it wouldn't change if you needed your fans to speed up or slow down. You also ran into problems with some fans that wouldn't run properly at lower voltages. Most fans can run at low voltages, but they require a higher voltage to get them started up first. You often hear every fan at maximum speed for the first second when you start a computer because it's getting everything spinning first before it lowers the voltage. So after-market fan controllers became popular because you could use a variable resistor to change the voltage to a fan, usually controlled by a manual dial on the front of a machine.

PWM stands for pulse width modulation which does something completely different. Instead of changing the voltage fed to the fan, it simply switches the power on and off very fast. This on/off signal is what gets sent over the fourth wire. This means the fan still gets the full 12V blast to get it spinning, but changin the voltage pulse also gives much finer control over how fast the fan spins. This is why it's popular for CPU cooler fans, because you get exactly the speed you need without any excess noise. Some third-party fan controllers can take in a PWM signal and then repeat that same signal to every fan on them. This lets your mboard's CPU fan controller work for all the fans in your system.

However PWM isn't quite as necessary as it used to be because most mboards now can dynamically change the voltage they send out over their 3-pin headers. If you check in your BIOS, you should see a fan control section that lets you set desired fan speeds and maximum temperatures. However, your board is a little old, so it might not have all the fine-control a current mboard would have.

 

[Rogue Leader]

His board has ASUS Fan Xpert on the CHA_FAN plugs which allows for control I believe. PWR FAN is 100% all the time.

 

[DonkeyOatie]

Yes. The PWR fan is 100% and the rest can be controlled from the motherboard.

However, if PWM costs the same as non-PWM, get PWM.

 

[RedJaron]

His board has ASUS Fan Xpert on the CHA_FAN plugs which allows for control I believe. PWR FAN is 100% all the time.

Right, but it's a five-year old version of it, so I don't know if it has all the control features current Asus boards do. My Z68 board can only set static levels to most of my fans whereas current ASRock boards I've reviewed allow a full fan curve to be set for their 3-pin headers.

 

[kontrol]

I think it's crystal clear guys. Lot of thank to you. Hope I can select more than one answer as the solution!
edit: looks like I can't, you guys were all helpful but I selected the single answer that resumed most of my questions!