Using a PWM fan hub with the MSI Z97I AC Gaming motherboard

[maxfarob]

Hi, I was wondering if it was possible to connect a PWM fan hub (like this one) to the 4 pin SYS_FAN header on the MSI Z97I AC Gaming motherboard to have 2 or 3 fans running at controllable speeds. I've read some posts saying that it can be unsafe to connect multiple fans to a single header as it might short out the board. Also, will I need 4-pin fans?

Thanks in advance!

 

[Karadjgne]

Yes, that'll work pwm fans if connected to a pwm header.
Yes you'll need 4pin pwm fans, to run a pwm signal, you need to keep same connectors, 4pin or 3pin, don't mix the 2,they aren't compatible.

Multiple fans depends on the fans. All fans come with an amperage rating, and the mobo headers are usually rated at @1A. My case fans are rated at 0.18A, so I'd be easily safe running 3 fans, should be able to run 4, but really not recommended as it's just an assumption of a 1A header, it could be 0.8A. So you can run upto the rated 4 fans, depending on if they add up to less than 0.8A for safety reasons. There are fans out there that require greater than 0.5A, so in that case, it's not recommended to run multiples of those fans on a single header.

Some fans just have a wattage rating. Just divide by 12 to get the Amp rating.

 

[Seanie280672]

If you get this one instead, it has options for 8 PWM fans, but the added bonus is the fans get their power direct from the Psu, the cable supplied with it splits into 2, one part contains the power cables with a molex connector, and the other part, the 2 signal cables go off to a 4 pin connector to plug into your motherboard header, takes the worry out of how much power you're drawing through the motherboard.

http://www.candccentral.co.uk/phobya-pwm-8-x-4pin-splitter-81136.html?cat=529

 

[maxfarob]

Yes, that'll work pwm fans if connected to a pwm header.
Yes you'll need 4pin pwm fans, to run a pwm signal, you need to keep same connectors, 4pin or 3pin, don't mix the 2,they aren't compatible.

Multiple fans depends on the fans. All fans come with an amperage rating, and the mobo headers are usually rated at @1A. My case fans are rated at 0.18A, so I'd be easily safe running 3 fans, should be able to run 4, but really not recommended as it's just an assumption of a 1A header, it could be 0.8A. So you can run upto the rated 4 fans, depending on if they add up to less than 0.8A for safety reasons. There are fans out there that require greater than 0.5A, so in that case, it's not recommended to run multiples of those fans on a single header.

Some fans just have a wattage rating. Just divide by 12 to get the Amp rating.

Thanks for your answer. It looks like the case that I'm thinking of getting (Fractal Design Define Nano S) comes with 2x 3-pin fans and a fan splitter. The fan splitter only has 3 pins - would it be safe to connect this to the 4 pin SYS_FAN header? I realize that this won't allow me to control fan speed, just exploring alternatives.

 

[Karadjgne]

Well, there's 2 different fan designs. 3 pin are voltage regulated, the fans usually range from 7v-12, the higher the voltage the faster the fan spins. 4pin pwm are quite different. They use a 12v constant voltage and the pwm signal stops/starts the fans in a perpetual cycle of trying to get to full speed. This results in normal 20% - 100% speeds possible, whereas the 3pin generally run 60% - 100%.

So while it's perfectly safe to put a 3pin fan on a 4pin header, you'll have 0 control by pwm signal, so the fan will always spin at 12v 100%. However, that said, most better mobo's option out the header, you can use either fan design at will, if you put a 4pin fan on it, the header acts as pwm, if you put a 3pin fan on it, it acts as a voltage control header. So either design will work on those mobo's. Not sure if your mobo does that for that sys_fan header, but there's a very good chance it does, so you'd not only be safe, but you will have some fan control too.