No fan speed control on new build - S340 case and Asrock B250M-HDV

[Nvidiaguy07]

Ive got a new PC build that is all together and is working fine - besides the fact that none of my case fans can be controlled in the bios.

Adjusting the cpu fan works (H212 evo), but the fan rpms in the bios stay exactly the same when set to silent or even full power.

Fans are all the 3 pin variety. Ive got 4 fans total. 2 fans are the ones that came with the case, and 2 are 140mm rosewill fans bought from amazon: https://smile.amazon.com/gp/product/B00K960BFY/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

The motherboard has 2 fan headers, so Ive got 2 pwn splitters on each, so the 2 120mm on one header, and the 140mm on the other. https://smile.amazon.com/gp/product/B01EF9OI0O/ref=oh_aui_detailpage_o07_s01?ie=UTF8&psc=1

Any reason why im not able to alter the fan speed? I have a similar computer that does change the fan speed based on cpu temp. I would even be happy with just having them run at a lower speed all the time - ramping up and down to cool the PC down isnt all that important to me, but according to the bios it says its a feature.

Any idea why I cant do this?

 

[Wellcky]

Since your fans are all the 3 pin variety, and the board is, I believe 4-pin for the fan, I'd try connecting them to the last 3 pins on the board the first pin is the ground for the fans (from right to left) and see if that works.

 

[VirtualLarry]

It is not at all unusual for a budget (B250) board, to contain only one 4-pin PWM fan header, for the CPU fan itself, and then a smattering of 3-pin (potentially voltage-controlled) fan headers for System / Chassis fans.

 

[EXCellR8]

you can easily add a cheap fan controller to the system for around 20 bucks.

most people typically run chassis fans at full speed anyway

 

[Paperdoc]

Your problem is very common, and its cause known. Its fix depends on what you have.

The root cause is that a 4-pin fan header that actually uses PWM Mode to control its fans can NOT control a 3-pin fan. That fan type can be controlled only using Voltage Control Mode (aka DC Mode). From what you describe, it appears the mobo fan headers you are plugged into are using PWM Mode

The easiest solution IF it is available is to re-configure the fan headers in BIOS Setup to use Voltage Control Mode or DC Mode. SOME mobos allow you to set that option on each SYS_FAN or CHA_FAN header. So look for that in BIOS Setup.

If that's not available, you have three other choices.
1. Ignore the situation and learn to live with it.
2. Buy new 4-pin fans and replace all those 3-pin fans.
3. Buy a particular fan hub called the Phanteks PWM Hub:

https://www.amazon.com/Phanteks-PWM...d=1493915787&sr=8-1&keywords=Phanteks+PWM+Hub

This device has one cable that plugs into a SATA power output connector from the PSU for all the power its fans need, and another that plugs onto a mobo 4-pin fan header that MUST be operating in PWM Mode (which yours seem to be doing). (The instructions with it specifically recommend that you plug it into the CPU_FAN header, but you do not need to do that.) Then you plug all your case ventilation fans into the Hub's ports, making sure that the white Port #1 has a fan plugged into it. The Phanteks PWM Hub uses the PWM signal from the mobo header to create its own group of six 3-pin ports that operate in Voltage Control Mode, exactly what is needed to power and control 3-pin fans. So using this device is a way to control several 3-pin fans from one header that can only use PWM Mode for fan control.

Post back here the exact make and model number of your mobo. With that we can look up its capabilities and advise exactly what you can do.

 

[Nvidiaguy07]

The motherboard is an ASRock B250M-HDV. Heres a screenshot of what the fan headers look like. https://ibb.co/eqUYO5

 

[Paperdoc]

Thanks for that. The manual indicates that the two CHA_FANn headers operate only in PWM Mode, so they cannot control the speed of any 3-pin fan. Such fans will only run at full speed all the time. So, you have the three choices I mentioned previously. The last one - using the Phantks PWM Hub - will give you full control, and is likely cheaper than replacing four fans. I outlined how to hook that up. Just one additional hint, based on an item shown in your mobo manual. On p. 62 and 63 it shows options in BIOS Setup for the Chassis Fan1 Temp Source and for #2. Whichever you use to connect to the Hub, make sure it is configured to use the Motherboard temperature sensor, and not the one inside the CPU.