If you're not utilizing all 7, then it seems to me that you're not using the full potential of the processor. Seems like you either need to come up with some funky way of utilizing them all efficiently, or you're wasting a lot of that fancy, expensive processor.
If your game really needs to keep the CPU at 100% load all the time that's your thing, most games will make sure there's some percentage of CPU time unused in an average situation so a peak situation is less likely to drop the framerate. Never mind that it's physically impossible to keep a CPU at 100% load in any real-life situation because of bottlenecks.
It was kind of like in Donnie Darko when he and Gretchen...
Um, who's Gretchen? In that movie, I mean. No such character listed in the IMDB cast list. I know who Gretchen is in Faust.