Comments on: Help me cool a computer cabinet.

Question: Help me cool a computer cabinet.

filmgeek — Mon, 13 Nov 2006 06:39:45 -0800

There's a computer stashed inside a desk cabinet. It's too hot inside the cabinet. What to do?

My brother's computer is running too hot.
The computers fans are moving air...but since this is inside of a closed cabinet, the cabinet area is gets very hot (which means the computer's fans are only moving hot air).

Obviously, I want to try to cool down the cabinet.

The project I've started is adding some fans to the non visible side of the cabinet and some holes at the bottom of the opposite side.

The problem: how to power them. The fans are the standard computer fans with the 4 prong plastic power connectors meant to go to a power supply. As I plugged in an extra power supply (standard to a computer)...I realized that I need an on/off switch that would normally connect via the motherboard.

And at this point, I'm lost.

I know basic wiring/stripping/soldering. I don't know enough about capacitors and the like. Radio shack and a comp usa are nearby.

Hope me hive mind.

By: fake

fake — Mon, 13 Nov 2006 07:04:10 -0800

Hey Filmgeek. Well, first of all, if you already have a standard power supply running, good on ya. But you know what's better than a standard (ATX) power supply? An old AT power supply- they have a switch to operate them. So your best (meaning simplest) bet is an old 486 with a switched-with-a-normal-switch power supply.

Now, that's not your only option. It's not that hard to modify an ATX power supply with a SPST (single pole, single throw, available at Rat Shack) switch to turn it on and off. On the motherboard connector, there is a green wire, pin #16. Connecting this wire to the black wire (ground) will turn the power supply on.

There's a needlessly complicated tutorial here: ignore all the stuff about binding posts and LEDs, and just pay attention to how they wire the switch. That should get you up and running.

By: fake

fake — Mon, 13 Nov 2006 07:06:05 -0800

Another note, I'm sure you've already thought of this, but I've had really good luck just knocking out the back of such cabinets, usually they are that thin paperboard stuff, and the back really isn't important. Seems too obvious to be of any use, though.

By: backseatpilot

backseatpilot — Mon, 13 Nov 2006 07:44:40 -0800

What about just plugging your extra power supply into a power strip, along with the computer and monitor? That forces you to turn the fans on when you turn the computer on.

By: upc_head

upc_head — Mon, 13 Nov 2006 07:55:17 -0800

As long as your PC has power to spare (IE 350W or more), Why not look into getting an extension for one or two of your internal connectors.. a long one. say 18", and run it out of a hole in the back of your PC? Plug it into another extension connected to your fans, and you can just connect it when you load and unload the PC from its space.
Some of the less "consumer" stores have extensions like this for 24" cases and such where stock power cables can't reach.

This would let you shut down the other fans whenever the PC is off.

By: fake

fake — Mon, 13 Nov 2006 07:58:20 -0800

Or yet another possibility- get an ATX to AT adapter like this one.

Further still, you could simply use the computer's existing power, using a Y extension cable like this. Bonus that you don't have to worry about turning the fans on and off, they'll be automagic.

By: fake

fake — Mon, 13 Nov 2006 07:58:34 -0800

Or what UPC said.

By: StickyCarpet

StickyCarpet — Mon, 13 Nov 2006 08:22:07 -0800

If you find the noise from the additional fans to be a problem, you might consider this (unorthodox) method that I use: I got a couple of largish box fans that are meant to run at 220 volts and wired them up to a regular 110 volt plug, at this voltage they run slow and quiet but still move a reasonable amount of air because they are industrial fans that blow like crazy at the correct voltage.

By: Good Brain

Good Brain — Mon, 13 Nov 2006 08:28:20 -0800

Pull the power from the USB ports.

By: AstroGuy

AstroGuy — Mon, 13 Nov 2006 08:41:59 -0800

I had exactly the same problem. I bought one of these, mounted it on a hole cut into the back of the computer cavity (at the top, blowing out) and made another hole near the bottom. The cavity is now 12-14 degrees C cooler. Like Good Brain said, this fan runs off power from a spare USB port.

By: AstroGuy

AstroGuy — Mon, 13 Nov 2006 08:42:38 -0800

(I meant to say the computer is running 12-14 degrees cooler.)

By: Chuckles

Chuckles — Mon, 13 Nov 2006 08:58:36 -0800

You definitely want to use the computer's internal power supply. Powering up a whole AT/ATX supply just for a couple of fans is very wasteful; you'll be burning 50W when 10W would do.

I'm not sure about the USB port.. It is possible, but your typical 12V case fan isn't going to run off 5V very well (some people put case fans between the +5V and +12V line, to create 7V - a lot more than 5V). Also, the total output power of your USB ports is pretty limited, and you might want it for something else one day. Not such a big deal, but better not to create future hassles for yourself.

If you really don't want to use the computer's internal power, get an AC adapter. Most hubs and routers use 12V 1A adapters, an extra from an old/dead router should work perfectly.

By: kindall

kindall — Mon, 13 Nov 2006 11:32:33 -0800

If you have a Fry's electronics nearby, they have those "universal" wall-warts that puts out up to 12V at 1A for like $7. If you don't have a Fry's nearby you could order one online but you can probably find similar at Best Buy or wherever. (Just make sure it's a full amp.)

The reason I suggest this is that the voltage is adjustable so you can turn down the fan speed. The 1A rating should be fine for a fan or three.

BTW, use the biggest fans you can; that way you can run them slower and still move plenty of air.

By: kindall

kindall — Mon, 13 Nov 2006 11:34:50 -0800

Whoops, that link in my post goes to the 300 mA one you shouldn't buy. I know they have a 1A one at the store, though.

By: QIbHom

QIbHom — Mon, 13 Nov 2006 12:52:03 -0800

A public library in the area had custom cabinets for the OPACs. They were having a lot of issues with hardware failure.

They took the doors off, and one of the staffer's husbands, who was in to woodworking, cut pretty patterns in the doors. It looked fancy, kept the computers away from gefingerpoken and kept the computers cooler.

By: flabdablet

flabdablet — Mon, 13 Nov 2006 14:51:48 -0800

ISTM that just knocking out the back of the cabinet would be more than adequate, and certainly worth a try before you go hog-wild with fans.

If you don't want to knock out the whole back, just putting a big hole right behind the computer's case exhaust fan, another one behind the power supply fan, and another one through the floor of the cabinet underneath the computer should be OK.

By: filmgeek

filmgeek — Mon, 13 Nov 2006 21:15:42 -0800

Thanks everyone. I went to rat shack, bought a smaller 12v power supply and set it up to power both fans. Good to bounce things off of you hive mind.

By: filmgeek

filmgeek — Mon, 13 Nov 2006 21:20:45 -0800

P.S. the back already had large holes, they weren't working.

By: flabdablet

flabdablet — Mon, 13 Nov 2006 21:44:22 -0800

If the roar of the new fans becomes troublesome, something else you could try is taping a couple of short ducts to the back of the system box, one behind the power supply fan and one behind the case exhaust fan, to lead the air from those fans straight out the holes in the back of the cabinet. The ducts don't need to be fancy - folded cardboard would work. Use short offcuts of PVC sewer pipe if you want something more deliberate-looking.

That way, the existing case fans will exhaust the warm air from the cabinet and force cool air to be drawn in to replace it, instead of letting the same stale warm air recirculate.