I'm using a Tsunami Dream, so the side fan is stuck there unless I want to see a nice big hole.
Do you think it'll be alright if I replace the old 1400 RPM fan?
According to the specs for this case on Thermaltake's web site, the front and rear fans on the case are identical. That means that the rear fan should also be pulling 110 CFM. So leave it alone.
The suggestrion about removing the side fan is not unreasonable.
You don't necessarily have to end up with a hole in the side of your case. You have two options here, assuming that you want to remove the fan.
First option is to replace the transparent plastic side panel that includes the extra fan with a solid metal side panel from Thermaltake. They will sell you one of those, and it will fit perfectly.
It is curious to note that the solid metal side-panel does not include a fan. I wonder why the clear panel does. Oh wait, that kind of panel is popular with a certain class of enthusiasts who want to show off how "neato" their systems are. They are suckers for extraneous gadgets, and something like a side-panel fan makes the system that much more "neato". They sure got your number. You paid at least $30 to $50 more for that clear side panel with the fan.
You can't put a fan in the top of your case because that is where your USB, Firewire and sound ports are located.
If you wamt to keep the clear panel but lose the fan, you don't have to end up with a hole in the side. All you need to do is get some plastic, carefully cut it to size to fit the hole left by the fan and glue it in. You could use a diiferent colured palstic, or get some plastic that has been doped to glow when exposed to UV or fluorescent light. Glue that in and install a very small UV bulb to shine on the plastic. And Voila, a really "neato" case. is yours.
Hope this helps.