try to find a dead mouse, then cut out the USB cable from there...
later use multimeter to find pin 1 & pin 4 cables and connect to case fan's power pins
as theoretical should work... so try it at ur own risk...

anyway, USB Pin 1 & Pin 4 only deliver 5V voltage, so a bit struggling for case fan to cool your laptop efficiently... in order to avoid any unnecessary damages, recommended to find a power adapter which deliver 8-14v DC output and plug ur case fan onto it...

This post has been edited by gkl83: Feb 22 2011, 01:33 PM

it just about voltage and amp...

if u paired with many case fan from 1 USB port, you may end up burnt USB controller (maybe, or other power supply components on mobo) due to overheat as USB port forced to delivery more power to operate case fans...

if u dont have any experiences about electric, better buy a power adapter instead as it will cut off if wires shorted or polarity connected wrongly... just cost RM10+ only from any DIY hardware shop...