I would just like to again thank everyone for their hard work on everything getting us to this point. After following ebereon's little guide ive tuned my cairnsmore1's to run at a nice level;

http://www.unstable.org.uk/images/temp/mpbm.png

This is powered directly from an old ATX psu (200W Max on 12V @ 8A (which should surely be 12V*8A=96W??))

However i have a small issue where I occasionally lose all 4 com ports (Win 7 64bit directly connected to pc) at random intervals. I have to disconnect the usb and power cycle the cairnsmore1's then reconnect the usb to get them back. The idea is to move these cairnsmore1 to my datacentre, to run off of one of my linux machines, so this is not an ideal situation if it continues to happen.

Ive changed the usb cable which seems to have helped somewhat (as you can see 20 hours from the image above), and ive ordered one of those recommended 35 port usb hubs to help also, is there anything else i can do? (I guess worst case i can remove the 5v from the usb cable and hook the atx up to the remote power bar).