How to build a 68040 CPU Fan

A number of people have been asking me for details about making their own CPU fans for cooling off their up-clocked CPU's. I went to the local Radio Shack, and for about $20 in parts, you can make a decent CPU fan by yourself.

Output Enablers now sells similar fans for cheaper than you can make yourself. You can get to their web page by clicking on the name above, or you can send them e-mail at oe@well.com.

Parts you will need:

Radio Shack part number Description Approximate price
278-766 Disk Drive Y-adapter
power cable (10")
$2.00
273-244A 1 9/16" DC Brushless
Micro Fan (12VDC input)
3.5cfm airflow
$14.99
some solder and
a soldering iron
a bit of electrical tape
some 5 minute epoxy
a 68040 Heat sink

How to make it.

1) Look at the drive y-adapter cable. Each of the connectors has a pinout that looks like this:

                                 Radio Shack     Standard
           _________             Color Code:     Pinout
          / o o o o \             1 = yellow     1 = +12VDC
          |_________|             2 = orange     2 = Ground
            4 3 2 1               3 = black      3 = Ground
                                  4 = red        4 = +5VDC
Please note that the wire colors may not be standardized on these parts. I'll be using pin numbers to identify wires in what follows:

2) Snip off all four wires for one of the arms of the Y cable. Snip them near one of the female connectors (the female connectors actually fit inside the male connector -- female refers to the electrical contacts, not the mechanical aspects of the connectors themselves).

3) Twist the Red wire from the brushless fan together with the free wire from pin 1 of the Y connector. Solder the wires together, and wrap them with electrical tape.

4) Twist the Black wire from the brushless fan together with the free wire from pin 2 of the Y connector. Solder the wires together, and wrap them with electrical tape.

5) Wrap the free ends of the other two wires (pins 3 and 4) in electrical tape so that they don't make contact with each other or anything else.

6) Mix a small amount of 5 minute epoxy and apply it generously to the small silvery "Radio Shack" logo on one side of the brushless fan. Be careful not to let any epoxy get outside of this silvery part, or your fan will not work when the epoxy is dry.

7) Lay your heat sink with the fins pointing up on a table. If you are using your Apple-supplied heat sink, make sure the clip that holds it in place is kept with the heat sink. Center the fan (epoxy side down) over the heat sink, press them together, and let them sit undisturbed overnight.

How to install it:

1) Turn off your computer and open the case.

2) Unplug the power connector from the hard drive.

3) Plug the power connector from the hard drive into the male connector on the fan assembly.

4) Plug the female connector from the fan assembly into the hard drive.

5) Power on your computer and make sure that both the fan and hard drive spin up.

6) Power down your computer.

7) Attach the heat sink to the 68040 in the normal manner.

8) Close up your computer and enjoy your fan-cooled CPU.


This file is copyright 1994 by J. Daniel Gezelter.