Tutorial written by : modchipsource.com (posted here with permission of author)

What you will need:

1 12 volt (dc) Micro Fan (example uses radioShack model #273-240) (40 mm).
1 Extension Power Cable (example uses radioShack model #278-7678) (25.4cm).
1 Hot Glue Stick and Gun.
1 Soldering iron and solder.
1 Electrical tape or other means of connection between wires.
1 Wire cutters / strippers.
1 File or Dermal.

Directions:

1/ Open Xbox and remove hard drive from black plastic housing

2/ Mark and Dermal out area to fit circular ridge of fan into the plastic housing for the hard drive.

3/ Drill small hole on right side (just above other two existing holes)

4/ Insert fan and push wire through drilled hole.

5/ Hot Glue either side to ensure fan will stay.

6/ Cut Extension cable to desired length (Example is approx. 2.5 inches total length from connector to connector) and attach fan wires to the orange and black wires of extension cable. (Yellow wire of hard drive and orange wire of extension cable are the same).

7/ Connect one end of extension cable to hard drive, plug in IDE cable into hard drive, mount hard drive to plastic housing, and plug xbox side power cable into extension side cable. Reassemble xbox to finish.

Finished and final Notes:
This mod is intended to help cool an otherwise overheating hard drive, when the original single fan does not supply enough circulation to adequately cool the hard drive. This mod has been tested to work and is only a guide. We don not take any responsibility for your particular installation. Perform modification at your own risk, as opening your xbox will void your manufactures warranty. As always Good Luck.