Fans. Seem to be a mixed blessing.
I filled this puppy up with fans, found them at a Wacky Willies fer cheap. I even have one which is a squirrel cage sitting in a PCI slot.
And still my computer, too, overheats unless I have on the AC, room style, on hot days.
AND, for some reason, the fans appear to move more dust in to the box, with the CPU fan blowing it into the heat sink.
So, I have to clean it out every so often.