Window Panel Bitfenix Prodigy

Rammy

Honorable
It will definitely have some sort of effect, as you lose the ventilated intake section. How much of an effect this causes is probably going to be dependant on what sort of graphics card you are using, but given the Phenom and Colossus versions of the case have solid sides, I assume it won't cause any major drama, especially given the Prodigy has better basic airflow than either.
 

Rammy

Honorable
Yeah that's more than I'd expect, but it might be an extreme example.

There's at least 5 XFX HD7870s, and not all of them have great coolers. You might be able to lower temps by adjusting your fan configuration too, depending on what you have at the moment.