Limits to exhausting heat with an in-line return fan?

[Costanza_TX]

My question is in regards to the efficiency of in-line fans for central A/C return. There is a room in my home dedicated to computer equipment, and recently I’ve installed a bunch of hardware which gets really hot (and I have it running for 60-70% of the day). A few years ago I had an 8” return duct installed into the ceiling of this room. I remember the guy who installed it telling me that if should I need more circulation in the future, I could have an in-line fan installed into this duct. So my question is this: are there residential return-fans available with enough of power to exhaust this heat from my room? The return-vent goes back into the central unit (in the attic); does this limit the amount of heat which I can return through this duct? Any feedback or thoughts would be greatly appreciated. Thanks for your time!

[beenthere]

The fan would work better in the supply.