Welcome to WebmasterWorld Guest from 3.228.21.186

Forum Moderators: open

How to control multiple fans with only one socket

     
5:32 am on Apr 9, 2019 (gmt 0)

Moderator from GB 

WebmasterWorld Administrator mack is a WebmasterWorld Top Contributor of All Time 10+ Year Member Top Contributors Of The Month

joined:June 15, 2001
posts:7845
votes: 95


On a recent PC build, I am having some heat issues. My plan is to add two additional intake fans to the front of the case to supplement my exhauster fan at the rear. The problem is, I only have two fan headers on the board (CPU and system1).

What I can do is use an adaptor to allow a Molex connector, from the power supply to power the two front mounted fans. The problem with this idea is they will be on or off depending on the power state with no speed control. Another option is to use a "Y" splitter to provide power to two fans from one header. This might be fine for only two fans total, but for a setup needing three fans, I think this would draw more power than the header is designed to provide.

I have a solution, and I know how it would work but would rather there was a pre-built version I could buy rather than build it...

Imagine a small box with several fan headers on it that could connect to several system fans. It has one fan cable that plugs into the board header. It then receives a feed from a Molex cable. The board will pass voltage to the box (probably pulse width modulation) and the box use transistors to open on each pulse forwarding a pulse of voltage to the motors.

This would allow several fans to be powered from the power supply, yet controlled by the board without putting any extra load on the board.

Does such a thing exist or should I get to work creating a circuit board and getting my "box" 3d printed lol.

Mack.
8:50 am on Apr 9, 2019 (gmt 0)

Senior Member from AU 

WebmasterWorld Senior Member 10+ Year Member Top Contributors Of The Month

joined:Aug 22, 2003
posts: 2266
votes: 152


Another option is to use a "Y" splitter to provide power to two fans from one header

Which is what I did - without any problems.

Internally I run 4 fans [not including CPU and SMPS fans] two run off the chassis fan pins through Y splitter, and I forget what the other motherboard pins are called.

Front and back fans drag fresh air in across CPU and RAM, two fans on top drag the hot air out. That includes on days of 46 - 48 deg C earlier this summer.

Unusual for April I had 30.3 deg C here today, 39C yesterday and I live two minutes from the NSW Central Coast ocean as the crow flies - 5 mins by car.

The new weather format. Anyhoo the fans have coped, although some dust extraction with a cleaner would help after several years. Otherwise no problems except a hiccup with some RAM.

Those fans speeds are controlled through the BIOS settings.

YMMV as they say.
5:44 am on Apr 10, 2019 (gmt 0)

Senior Member from US 

WebmasterWorld Senior Member tangor is a WebmasterWorld Top Contributor of All Time 10+ Year Member Top Contributors Of The Month

joined:Nov 29, 2005
posts:10456
votes: 1091


Fans only work if the intake/out-take area dimensions are the same, else "more in" with no way out won't do anything but build up air pressure inside the same.

Better solution is liquid cooled for the over-hot parts ... but that is not usually cheap ... or easy to install.

Some years back, with a particular system with heat problems, case was removed and an ordinary box fan was directed at it. Not practical for many ... and noisy, too! :)

Needless to say that system was used only until it could be replaced by something better designed for heat management!
4:36 pm on July 13, 2019 (gmt 0)

Senior Member from GT 

WebmasterWorld Senior Member 10+ Year Member Top Contributors Of The Month

joined:Mar 30, 2006
posts:1613
votes: 163


I experienced issues like this.

X2, fan pins, double fans, solved. Mmmm... the main parts getting hot like the processor have speed variations, I would prefer one intake fan with absolute fixed speed. The size and speed of the fan (vent amount) is related to the exit of your box, so if you increase air intake you should increase the exit too.

One non-pretty solution I end up applying was removing the case, working with an open CPU. It's not pretty, and it shouldn't be as effective because there is no closed fixed air flow but... it worked like a charm, no extra vents or fans needed.

Another solution (I don't know the specs of your build) was removing everything including the thermal past, perform a full cleaning procedure and put some NEW fresh thermal past. Worked like a charm, never needing any extra fan again (and it was way more quiet).

Extra solution: a bigger heat sink. Yes as it sounds, same vent, same fans, etc. But just a bigger heat sink.

I've done all of these on CPU's, laptops and electronics (non computers) that have heating components on closed systems. I rather stay with bigger heat sinks.
7:13 am on July 14, 2019 (gmt 0)

Senior Member from US 

WebmasterWorld Senior Member tangor is a WebmasterWorld Top Contributor of All Time 10+ Year Member Top Contributors Of The Month

joined:Nov 29, 2005
posts:10456
votes: 1091


Make sure the connective paste is well applied (and appropriate!) but in the long run, liquid cool is the way to go.

That and boards/cpus that actually work as thermally designed.

Also ... nothing wrong with heat (it is a by product of the process) as long as the components are spec'd to handle same. If not, get different components!

But you are trying to save an existing box that is work fine otherwise, take out any slot covers, etc and put a "blower" on the front to exit the rear.