> My PC has recently developed a rather annoying buzzing noise that comes
> through the headphone (or monitor speakers) in certain situations.
Check the cables are plugged in correctly (ie, pushed all the way in - some
cables too, even new ones, may have been kinked at some point causing the
wiring inside to fracture and break the sound if the wire is vibrated by
movements near the wire). If it was a wired mouse I would say that probably
your mouse cable is disturbing the sound cable as you're moving it around,
but as you're on wireless, then that's probably not the case here.
I've noticed if the sound out is amplified greatly through any system then
you get some element of buzz - whether it be from the pickup and
amplification of fans inside the PC - components with fans transferring
sound through the mobo onto the soundcard / the wires connected to the
soundcard. Also it could be cheapo speakers / cables / duff sound card
drivers or even mouse drivers.
Incidentally when everything is really quiet, I can hear my wireless mouse
beeping with every moment I make with it - I guess I can just about hear the
wireless frequency it communicates on - not a loud noise or a hissy noise,
but a mild beeping noise nonetheless. In your case, it may also be where
this noise is being picked up and amplified by your equipment too. Its
really a process of elimination. Try a wired mouse, try another wireless
mouse, try driver updates, try a different amplifier / speakers / soundcard,
etc.
Good luck - I can appreaciate how annoying it can be - especially if you
listen to music whilst you surf.