DVDdoug:
This is, in many ways, intended to be overly engineered just to ensure that my precious PC doesn't get damaged.
I've never seen a PC physically damaged from "normal" overheating. If something literally burns-up, it's normally damaged before you get smoke & black-dead components.
I haven't had a CPU overheat in a long time... When it did happen (due to a "frozen" CPU fan) the CPU would slow-down to a crawl to protect itself and there was no permanent damage. I believe Intel & AMD processors both have over-temperature protection built-in.
In a mining rig the temperatures have to be pretty constant in order to maintain predictable ans stable mining hashes. The PC I'm building this for is my main PC at the moment, but is going to be the test bed for this design so I dont hinder the hash rate of the mining rig once its up and running. On the R-series GPUs from AMD that we're gonna be mining with, a couple degrees can mean quite a bit of monetary loss in the long run because of the automatic overclock that they have built in.
But for now I'm building this on my main gaming/work rig so that I get the kinks worked out on something that isnt really making me money.