So you essentially mean "gamer" style systems, wouldn't these comprise a growing percentile of the current PC industry/market?
I shouldn't think so. A much-reduced percentage would be my guess. Oh, my own sales of this sort of system have shrunk to practically zero in recent years, but I attribute most of that to other factors - primarily (a) my primary market is older than the average gamer, and (b) games bore me absolutely rigid and the only gamers who buy systems from me are the ones who don't mind me laughing at them for wasting so much perfectly good money on a ridiculously dear computer. that is a fairly rare personality type. In general, anyone intelligent enough to laugh at themselves in that way is too intelligent to play computer games much. (Mind you, the rare exceptions tend to be extraordinary characters, and are well worth knowing.)
But you are talking about the market in general. I reckon a much smaller percentage, as I said earlier, because of (a) the rise of non-computer gaming rigs such as Playstation and X-box; (b) the expansion of the market has swamped the gamers (who have been into it for a decade or more) with hordes of schoolchildren and grannies and others who would not have dreamed of having a computer of their own until these last few years, and especially (c) the fact that most modern games run perfectly happily on a standard run-of-the-mill home/business system anyway. The hard-core action games still require as much hardware as you can poke a credit card at, but most of the other stuff even works on a laptop, never mind a middle-of-the-road desktop.
In short, games systems are a rarity on the market. the only reason they get so much space on shelves and in advertising is that they are one of the very few parts of the market that still retain fairly high margins. Bit like power supplies really - those big, expensive black things we were talking about the other day account for maybe 5-10% of all PSUs sold - and about 98-99% of the reviews, advertisments, and discussion.
From your responses I guess that perhaps I'm over engineering my housing solutions, it's just that I often see people with their computers situated in their lounge room (traditionally a well heated room) and during winter room temperatures can exceed what would be considered a normal operating environment, factor in some intensive CPU/GPU applications like gaming OR video encoding and case (and component) temperatures rise again, it's like that old adage "If you fail to plan, you plan to fail" thus I plan to not fail in the sense of providing adequate hard drive ventilation
Better to be safe than sorry!
Actually, it's the summer temps you have to worry about. Winter temps, even in the most outlandishly carbon-wasteful of households, rarely go much above 25 or so. But in summer, inside temps of 35 are not uncommon.
The secret (as I see it) is decent passive ventilation - i.e., some holes somewhere low down in the case, usually at the front, and some more holes high up (usually at the back). Even if the PSU fan fails, the natural tendency of hot air to rise will usually be enough to stave off disaster for quite a while. Oh, and I try to make sure that people know not to block the vents up with thick loop pile carpet or similar - that's a bit of a trap!