I agree with LOC computer fans will not move enough air to push it out past about 24" of vent pipe. You may be better off using a larger vent pipe then the computer fan just to reduce the backpressure. I still don't think it will work worth a dam but that will at least give you a better chance of the little fan doing you any good.

Active carbon scrubbers are the very best way to deal with odor from growing and flowering plants.
Zandor Reviewed by Zandor on . my idea for odor control... ok so ventilation/odor control, ive been doing some brainstorming... I think im going to buy a computer fan... and connect a 3 in hose from the exhaust of the fan to a hole in my cabinet. That should successfuly suck alot of heat out and expell it into my room. Only prob is when the plant is flowering my room is gonna reek. So im going to sharper image and buying one of those desk size Ionic Breeze (~50$) and stick it inside. Plus, im gonna tape some dryer sheets up to the hole so the Rating: 5