The power supply in my G4/400 Sawtooth machine had a fan that was
dying.
The thing actually stopped altogether so I had to replace it.
I replaced it with a better, lighted fan but that's another story.
So long as the form factor, voltage, and cfm rating is sufficiently
high you should be good to go.
Some of the Thermaltake fans have fast speeds with ball bearing
mechanisms and lights so you can see the thing is actually going.
Just a though.
PC Hot rodding shops have this kind of thing, look around and
see what you can find.