[geeks] drive cage fan for Dell T105 server

[nate at portents.com]

> It has four cables, and I don't know what the other two are yet,
> besides power and ground.  I'm sure one is the speed tick, not sure of
> the other.

Four pins?  Likely to be for a PWM fan:

http://www.formfactors.org/developer%5Cspecs%5CREV1_2_Public.pdf

- Nate