Variable resistor for HS fan speed control?

[timje]

Are there any issues I should consider before I run over to Radio Shack and buy a variable resistor for slowing down my CPU's heatsink fan? I know I need to make sure it has enough juice to actually spin up, and (of course) that the CPU isn't running too hot...

 

[MrThompson]

A better solution would be to pick up a LM317 voltage regulator. The circuit is on the back of the package so you can buy the rest of the parts while you are at the Shack.

 

[timje]

What makes this solution superior? It seems that the popular 'fanbus' gadgets all use rheostats...

 

[MrThompson]

A rheostat is the brut force method. They are more expensive than pots due to the need to handle more current and dissipate heat. A voltage regulator circuit is designed specifically for this task and a much more elegant solution. Voltage regulators are the standard in electronics. Rheostats are a backyard hacker?s solution. You can find out more about LM317 circuits here. My multiple fan bay bus can be seen here.