Slow down fan speed

Pint · 10-24-2007, 12:29 AM

My PC is very noisy ..... I know you heard this 1000 times. - Sorry
how di I cut into my 5volt rail to supply my case fans? any pointers would be appreciated. I'm thinking of using the powersupplyfrom my spare USB headers on the motherboard.?

I'm also going to try a vacum pump to suck the air out (instead of blowing it in) and increase air flow. ( I can run the pump outside of the car)

and sit the case on a laptop G-Pad aluminuim heat exchanger to try and drop it another few degrees.

hopefully after all that it should be silent.

pRoFiT · 10-24-2007, 12:45 AM

Just pull 5 volts from a hard drive power connector. RED is 5V YELLOW is 12V and black is ground. Done.

1st. How are your fans connected now.
2nd. Not better but....Less power consumption from your power supply if you run your fans on the cars 12volts. Just my thoughts on that. but then you have 13.8 to the fans.

I would build a simple cheap 5 - 8 volt regulator from the cars 13.8 volts and connect the turn on to your accessory on switch. then run your fans from that. a simple lm7805 or 7808 can handle 1 AMP out and 9-28VDC in.

Maybe someone else has a better way to do it?

Pint · 10-24-2007, 01:01 AM

Thanks pRoFIT.
I will use the spare hard drive power connector option. I'm not to worried about the power consumption - My Fans are already powered from the PSU/motherboard.

I tried a voltage regulator for something else and I remeber it got really hot. I don't really want the additionaly wiring effort.....

One more question. I remember 3 wires that connect my fan. I'm assuming I can leave one of them connected to monitor my fan speed?

Grrrmachine · 10-25-2007, 06:55 AM

Very often 5V isn't enough to give the fan the required kick to get the motor spinning (try running two 12v fans in series and you'll see what I mean.)

Rather than chopping and splicing and crimping and bodging, why not just do what everyone else has been doing for the past 10 years and buy one of these:

Fanmate Fan Speed Controller

strohj · 10-25-2007, 10:48 AM

OR.. just get a newer ball bearing fan .. I replaced all mine even on my pc's at home.. its soo much quieter now...

Pint · 10-25-2007, 11:18 PM

Grrrmachine, I tried the fanmate, but I wasn't happy with it as i had to have more wires comming out of my PC and seperate controll units. If I housed them internally (not that I have the room), the heat generated by the controllers becomes a problem. They are no good for me, but they did prove slowing the fans down quitens them down enough for me.

Strohj - I had a look at alternate fans and decided not do that for two reasons
I've got two pretty good/new fans as it is (just a little too noisy for me).
Sourcing better fans proved to be quite difficult......

I'll stick with trying to run them on lower voltage with a heat exchanger to compensate for the decrease in airflow.

Thanks for your suggestions

NiSlo · 10-25-2007, 11:34 PM

Google for Speedfan. It's a software based fan controller

Pint · 11-03-2007, 06:26 AM

okay....
I tried Speedfan but it wouldn't work with my ITX machine.
also tried powering my fans with 5Volts but as GRRMachine hinted, they wouldn't start up.

I had a look at quiter fans - but I could'nt find them in Australia and shipping was going to cost me an arm and a leg so I gave up on that idea.

I've gone back to the Fanmate solution. I took the fanmate out of it's plastic and shortened it's cable then plugged them into my fans and squeezed them into my case.

I also screwed a laptop heat exchanger - which is really just a piece of aluminium - to the bottom of my case to help with heat transfer.

My PC is now running quite. Although a little hot. I'll see how it goes and as a last resort put in a vacum air pump to suck out air and improve cooling. I'll post some pictures when I get a chance tomorrow.

Pint · 11-04-2007, 06:43 PM

here's the heat exchanger and fan controllers

Moneyfink · 11-05-2007, 05:25 PM

5V is often not enough to kick start your fans, but 7V is
You make 7V by hookinh op the positive wire on the fan to the 12V rail, and the negative wire to the 5V rail. The potential difference is 7 V. I made a homemade fan controller for a case a while ago with a double pole single throw switch (i think thats the right name) anyway, I could select 12V, 7V or Off.....
So what I made was High/low/off That sounds like somehting that may be useful to you.
It cost me under 5 bucks as some fan controlers can cost $30. And if spce is tight this is more barebones

Rob Withey · 11-06-2007, 01:13 AM

Quote: Originally Posted by Moneyfink

5V is often not enough to kick start your fans, but 7V is
You make 7V by hookinh op the positive wire on the fan to the 12V rail, and the negative wire to the 5V rail. The potential difference is 7 V. I made a homemade fan controller for a case a while ago with a double pole single throw switch (i think thats the right name) anyway, I could select 12V, 7V or Off.....
So what I made was High/low/off That sounds like somehting that may be useful to you.
It cost me under 5 bucks as some fan controlers can cost $30. And if spce is tight this is more barebones

When doing this common trick, remember that your ground is no longer a real ground, and this may affect the behaviour of the 3rd wire used to sense the fans speed. This third wire is usually connected to the motherboard which is expecting the signal to be relative to a real ground.

Pint · 11-06-2007, 04:57 PM

I'm new to electrics..... I have two case fans.... is this what you mean?

_Dejan_ · 11-06-2007, 05:11 PM

Quote: Originally Posted by Pint

I'm new to electrics..... I have two case fans.... is this what you mean?

no. If you want 7V you must use 5V wire by molex for ground by fan(black) and 12V wire by molex for + for fan(red)

so if you look your picture you must change black and red wire on your fan.

P.S. About yellow wire on your fan I don't know if you can put it to motherboard and if you will see right values...

Pint · 11-06-2007, 06:14 PM

okay.... like this....

_Dejan_ · 11-07-2007, 12:47 AM

yes this must be ok