[SOLVED] How to control Molex fans speed?

[ThinkOutsidePC]

My 3 Molex chassis fans are "daisy chained" and connected directly to the PSU, making them run at 12v, full speed and very loud all the time... my Asus Prime B450M-A has a CHA_FAN2 empty connector right over the CPU_FAN connector, if i get a Molex to 3-pin cable can i connect them all on the adapter and then connect them to CHA_FAN2 so i can control their speed through the BIOS or another software? If not, are there any other solutions i can try? Thanks in advance!

 

[sds20020024]

Chances are that your motherboard fan header won't be able to handle all the molex fans daisy chained to it.
Are the cables coming out of your fans molex only?

If it's molex as well as 3 pin or 4 pin pwm, you could buy a fan hub like this

https://www.amazon.com/DEEPCOOL-FH-...&keywords=deepcool+fh10&qid=1613543322&sr=8-2

and connect your 3 pin/4pin pwm fans to this and power it with SATA power and connect the motherboard fan header to the pwm control header for controlling the speed

If it's molex only, I don't know of any fan controllers that have molex outputs for fans themselves.

 

[JohnBonhamsGhost]

your best bet is to purchase some modern fans with PWM control and a compatible hub to connect them to.

there really aren't many\if any options for directly controlling the speed of molex fans. possible there are some very old hubs that could vary the power therefore adjusting the speed of molex fans but i'd guess it's unlikely you'd find one.

 

[ThinkOutsidePC]

Chances are that your motherboard fan header won't be able to handle all the molex fans daisy chained to it.
Are the cables coming out of your fans molex only?

If it's molex as well as 3 pin or 4 pin pwm, you could buy a fan hub like this

https://www.amazon.com/DEEPCOOL-FH-...&keywords=deepcool+fh10&qid=1613543322&sr=8-2

and connect your 3 pin/4pin pwm fans to this and power it with SATA power and connect the motherboard fan header to the pwm control header for controlling the speed

If it's molex only, I don't know of any fan controllers that have molex outputs for fans themselves.

Yup, no 3-pin, 4-pin or whatsoever, only molex; i would still try to connect them to the mobo header but i'm scared i may fry something as i've read some fried mobo stories like that, well this is what happens when you cheap out the case on a pc build lol, thanks anyways

your best bet is to purchase some modern fans with PWM control and a compatible hub to connect them to.

there really aren't many\if any options for controlling the speed of molex fans. possible there are some very old hubs that could vary the power therefore adjusting the speed of molex fans but i'd guess it's unlikely you'd find one.

I wish i could afford some right now but oh well my current fans aren't really that loud, thanks anyways

 

[cryoburner]

Molex has a pin providing 5v in addition to the one providing 12v (and two ground pins in the center). If the fans will run suitably at 5v, one option is to simply rewire the fan's molex connector to connect to the 5v line instead of the 12v one. This will typically make a case fan nearly silent, though it will be running notably slower, and in turn moving less air. This was a fairly common mod back when molex case fans were the norm, and is likely to be safe so long as you don't short wires together in the process. Some fans might not be able to start at 5v though.

There's also a method of rewiring a molex fan to run at 7v, but it could potentially cause damage to some power supplies, so I wouldn't recommend trying that.