I would tend to agree that SPCR is too forgiving when it comes to HTPC noise. I *do* notice my HTPC drive (WD Green power) from time to time, even though it probably measures less than 23 [email protected]
In a room that was too quiet to measure (i.e. <15 dBA), even quiet noises are still audible, and can irritate.
That said ... *any* extraneous noise (talking, music upstairs, any multi-media use of the HTPC) is enough to cover the ambient noise. I notice it when I'm loading media; if anything is playing it's silent.
However, with a louder fan ... I definitely think it would be audible during quiet sequences / pauses in music, despite being located behind my TV.
One thing I should clarify: I don't think Mike is advocating that you shouldn't try and silence your HTPC to the best of your ability, or that noise isn't a criterion for evaluation. We specialize in noise ... and that involves thinking beyond just a "noise=bad" mentality. The fact is, there *is* a difference in how noise is perceived from an HTPC vs. a tower machine. That 3m vs. 1m distance *does* have an effect, as do the ambience, the conditions of use and the "quiet room" issue.
We would be remiss in our duty to explore the world of computer noise if we did not raise this issue because our analysis would be incomplete. Our 1m measurement distance is designed to simulate an actual usage situation to the best of our ability, but that situation is not the typical one for HTPCs. You will note that the section called "Acoustics around a Media PC" does not actually draw the conclusion that some of you have jumped to; it doesn't say that noise doesn't matter for HTPCs. All it says is that the environment around HTPCs are typically noisier than most tower PCs.
Now, perhaps that does imply that noise matters less for HTPCs (and perhaps I am missing another part of the article where the "noise doesn't matter" idea is stated more explicitly). All that means is that you can now put a more powerful (or more compact, or allocate resources for a huge heatsink to something else) computer into the same system and not worry about the constraints of silencing, because, once the noise is below ambience, there is no effect advantage to be gained. It also means there's more tolerance for changes in noise when the system is playing media ... i.e. a warbling fan that kicks in under load really doesn't matter as much.
I think there's considerable room for debate about *how much* difference there is between the silencing requirements of an HTPC vs. a tower, but please don't get upset simply for noticing that there is a difference ... we wouldn't be doing our job if we took a "lower noise at any cost" attitude. Past a certain point, this is obsession, with no real benefits.