Ok I tried unplugging a few things.
CPU fan: makes just a little noise but not a major contributor to the overall noise (easy to tell this also because it is so far away from the bulk of the noisy components)
Case fan: definitely runs with some vibration noise - but also doesn't seem to be a major contributor to the noise. I'm sure a replacement could be quieter.
Listening close by to the unit for directionality of the noises doesn't seem to pinpoint the PSU fans in particular (eg. listening just outside the PSU outlet grill I can hear the fan whirring but there is a lot more noise (higher pitched) if I move my ear back towards the open internals.
So I kept hunting:
Additional HDD: disconnected the (unsecured) HDD and removed it all together. It was making a bit of noise - things were not particularly quieter per se, but the noise was 'less busy' without this drive whirring and clicking
Original HDD: I disconnected the data but couldn't easily pull out the power connection. I powered the unit on with this configuration and after the drive had spun up and the computer displayed the ''no system folder' icon there was indeed a bit less noise going on.
I also put my ear near the optical drive (actually the very first time I switched on this machine I hoped what I was hearing was a noisy optical drive with a disc in it - alas there was not disc in the drive!). There did seem to be some noise coming from here - only a small amount and it was hard to tell if it was reflected sound (so many hard flat surfaces in here! I haven't tested this drive apart from opening & closing the tray ... but I've been surviving without an optical drive on my DAW for a while now so maybe I can do without it. (I'll try disconnecting some other time as I think the whole housing will need to come out to access the cables properly)
So, my hypothesis so far is that my noisy machine is a combination of several components all contributing to a symphony of whirring and purring - AND - I think the casing is acting as a resonator for all of this noise.
What can be done? You tell me but here are my theories:
- replacing all fans
- disconnecting the optical drive
- replacing HDDs with SSDs (I've been putting up with the HDD noise in my G3 iMac for a while so not sure I'll actually do this)
- using rubber mounting to decouple components from the metal casing
- what about removing the plastic side covers from the machine? Has anyone ever tried this? Seems that blowing air into the cavity between the metal case and the plastic side wall is a bit weird and I suspect these gaps give some acoustic resonance.
*if* I can do all this (I'm pretty nervous about the yellow warning sticker on the PSU!!
![Embarrassed :-[](http://macos9lives.com/smforum/Smileys/default/embarrassed.gif)
), *and* I find an out of the way place in my room with a bit of baffling (eg. behind the main desk sitting on a rubber mat, maybe with some acoustic foam nearby reducing the noise in some directions while still allowing airflow) then *maybe* this machine could be the workstation I've been dreaming of!
I definitely don't have time to do all of the above but I have been bitten by the bug now and REALLY want to try - it just seems to put me that much further off from actually making any music - I can't quite figure out whether this matters or not as long as I'm having fun
![Grin ;D](http://macos9lives.com/smforum/Smileys/default/grin.gif)
I welcome all your thoughts!