Originally Posted by Derby92
All the dead space between the holes is blocking a good portion of the air flow. If you cut it out you can increase the air movement dramaticly.
I marked the places in red that need cut out. If you do this you can get wire grills to keep fingers and paws out.
The blue part is a massive air leak. It creates a air flow short circuit. Air comes in goes straight up the back wall and right out the back fan. Doesn't help with the rest of the case and the cpu.
Now speaking of the temps fluctuating on the cpu, you could and most likely have a fine coating of dust on the heatsink. Power down the system and clean the heatsink and the rest with canned air. Hold the fans with a pencil to keep from over spinning them.