On Mon, 03 Oct 2005 08:50:32 +0100, Terry Pinnell wrote:

I'm getting a sort of 'beat' effect from my PC. It seems to have been
triggered (or maybe just increased to a level at which I've become
aware of it) by adding a new (third) HD.

I'm at my desk, and the PC is on the carpet 3 feet away, at the side
of the desk. I can just hear this beat from here, behind the familiar
high frequency fan and HD spinning sound. Kneeling on the floor with
my ear by the PC case, I can hear the beat distinctly, at about 1
cycle per second. But my real gripe is that directly below, downstairs
in the lounge, it's surprisingly distinct. By no means deafening, but
it is intrusive. I'm aware of it even while watching TV. This is
through carpet, underlay and 2 layers of plasterboard.

It's the resonant frequency of the floor itself. I'm ass-u-me-ing that
you're talking about the beat frequency, which sounds like, wOwwwOwwwOwww...,
is that accurate? If it's just going thumpa-thumpa-thumpa, then you need
to fire your yard boy. ;-P

Go either to a scrap yard or a construction site, and get something
very massive, like a paving tile or slab of metal, put it on the floor
where the computer is now. Put some kind of acoustic insulation on top
of it, like get a discarded wet suit or some old inner tubes, and put
the computer on top of that pile. Don't use "acoustical tile", because
you want the opposite of rigidity here.

Good Luck!
Rich

(of course, you could overwhelm it by playing that tape of the barking
dog that seems to come up here periodically. ;-) )