Well, there was a lot of dust inside. I have a plexi window on the side, and I can see it. I was gonna get one of those cans of dust-off, but the more I thought about it, the more I realized that I had something better.
A big-ass air compressor. With a freakin 12-inch leaf-blower nozzle.
Well, it most certainly got rid of the dust. I was able to get my processor temp down to 51C with the cold air blowing on it.
Currently it's running at about 63-64C. Much happier. Though the power supply fan is starting to make the chattery noise that I so don't like.