I have a 1kw enermax PSU and it was quite loud, because the fans was a big powerfull thing made to cool the PSU at full load, but since im only running 1 GPU i had to replace it with quieter much less powerfull fan which now runs silently. If ya decide on a high watt PSU ide ask around on the forum first to make sure it runs quietly if ya bothered about keeping ya rig silent.
You'll probably need more than a 1000w for 4 high end cards with a 2011 cpu (and overclocking). Are you really sure you're going to get 4? Not many people do even if they think they will![]()
The AX1200i which I have is made by Flextronics, Mine doesn't suffer from coil whine but that's not to say it doesn't exist on this range / the AX1200i.