• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

speed control big fans, three wire

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.


New Member
Aug 8, 2017
I've built a case to battle dust in my basement for a couple of servers. I ran into some ... measurement problems <face-palm>, but it's close to done anyhow.

I installed four monster case fans, Bitfenix 230mm newegg, and a 12 volt power supply newegg. I snipped all the three wire ends off, and twised two of the three wires together with the 12v power supply. All fans light up and spin, but very slowly. I'm sure they can blow faster, and I need them to.

Now I'm regretting cutting all the ends off these fans, but I think I can remedy the situation. I'd like to tie in a manual speed controller like this one newegg that also has a temperature sensor in it, which is nice. This one is powered by Molex connector, a whole power supply, that I'd like to avoid buying and installing. it will take up a lot of room in my cabinet. Perhaps only four of these would fit the bill newegg but only two input pins would get the 12v power, while the speed input gets nothing. All three out wires would go to each fan.

I'm open to suggestions here of course, including rethinking this whole thing and going a different route. But I do like the idea of an easily replaceable/cleanable filter that will take care of all dust in my servers. They definitely need something because they're going to be living in my basement for the foreseeable future.

The project so far: https://goo.gl/photos/eMYntioGmeJAY7gb8


  • NpPzH.png
    34.5 KB · Views: 50
Last edited:


Premium Member
Dec 6, 2010
The max speed for those Bitfenix 230mm fans is 900rpm, that's the max speed your going to get. But don't think it's not moving a lot of air, if all that air had to go down to a 4" duct, it would be moving fast.


New Member
Aug 8, 2017
Thank you! I'm not sure what RPM they're at right now, but it doesn't seem to be very fast. I can tell that they don't do what I need them to do. Perhaps a whole different type of air mover, like a little blower? newegg. Something that will provide enough pressure to pull air through the filter and keep the temperature in the cabinet reasonable.


Mar 18, 2015
just to double check you fans you could try hooking them up to the other positive wire on the molex plug and see if they turn faster. You wont harm your fan, the fan with either turn faster or slower and confirm that you have everything plugged in correctly. However if it is already moving at its highest speed then you will have to look into other options for fans. I will say though that Ive had a couple of those BitFenix Spectre and Spectre Pro's , and they are solid fans compared to others. Maybe better placement will get you what you want from those fans? I cant think of any off the top of my head that offer that kind of CFM at that low noise. Even if noise isnt an isssue, 97cfm is hard to beat.