In my server closets I buy my own chassis with an easy to remove air filter on the front of each chassis, about every month I take it to the sink rinse it out, shake off the excess water and put it back. The closets have their own independent AC and room monitor with alerting sophisticated enough if for some reason the AC quit Servers would begin treating it like a power failure and begin shutdowns.
But for the poor PCs sitting on the floor of 100s of users all working as digital air filters. Unless regular maintenance is done (the dust storm blow job with the air compressor) they crash within 6 months to 1 year.
I really like the idea of liquid cooling. Just leaving a rig that I'm setting up for some running 24/7 with 2 8800GTX, QX9770, 2 Seagate 1TB, 3, WD 150 Raptor, evga 680i mobo, Tagen 1100W PSU 2 19" Dell 2007WFP in portiat mode sandwiching their 30" model in the middle.
Compared to last year, my electricity bill increased by 40% for this month My Kill-A-Watt reader registered an average 600W, but the heat would activate the main HVAC in my house much more often. All in all to run this rig costs close to $100 per month in energy costs.
If I could easily get that heat outside of the home, then I would only be expending 600W for the computer and saving 3KW each time the HVAC kicks on.
Another thing, the Cooler Master CMStacker is a POS. At least in the desert, it is nothing more than a dust storm in a box. So far I am using a great quality filtered rackmount chassis, but he wants CM with pretty lights lights. I'll show him where to the canned air is in costco and how to make small dust storms on his front porch every month.
Sorry for not having much of a point, my ambien as begun to kick in and will be typing in my sleep soon.