Originally Posted by Majinwar
The 8800 will be sucking air from the inside of the case, and blowing it out the rear of your case. You want the side fan to pull fresh air from outside into your case.
It depends entirely on your setup and what GFX card you're using.
For instance, the 9800 GX2 pushes air out of the side of the card, rather than out of the expansion slot vents on the card's rear.
If your side fan is being used as an intake in this case, your card will run very hot as you're trying to push the exhausted hot air back across the card's surface.
I've found that as a general rule, if you have the airflow of the case moving from front to rear, with the side and top exhausting, you can't really go wrong.
As for any new high end card, i'd reccomend using the side fan to exhaust the hot air from around the cards regardless.