I hate to ask and I've been trying to ignore it, but it's been bugging me and I haven't found any info online. I'm wondering if a 120mm fan will fit in the front of the Coolermaster Centurion 5. It has an 80mm fan standard, and it doesn't look like there's a lot of room to fit anything bigger. The screw holes probably wouldn't even align. I'd crack it open and look but but I don't have the tools here with me. My system has an average temp of 60 degrees C and my 8800GTS averages at 70 degrees C. I'd like to lower each by 10 degrees at least. I also thought I could put a fan on the side vent below the air duct, but it looks like for some reason my model doesn't have the screw holes to mount a fan like other models do. I don't see what the point of the vent is without mounting a fan, though.
Any cheap suggestions for cooling my system and GPU? Should I even worry about it at these temperatures? I don't want to go crazy with water cooling and $50 fans. What I'd really like is to somehow get an 120mm fan up front for intake to replace my 80mm one. Otherwise, the only thing I can think to do is drill through my side door and make my own screw holes to install a fan on the side vent, but I have no experience doing that and I worry about the increased amounts of dust in the case that could lead to.
Are there any non-intrusive ways to mount a fan inside a case without drilling holes? And is fan filter type important or will any cheap filter do the job without hindering airflow? Should I even be worried about my system and GPU temps? My CPU temp is usually a cool 30-40 degrees C. I think my system temp is only jacked up because I can feel the heat that my 8800GTS traps at the bottom of the case.