new 27" iMac, USB3 troubles
I have a new iMac and weird things have happened with the USB3 ports since day one. At the moment I have a USpeed 4-port USB3 hub and when the iMac starts up, the hub goes onto the USB2 bus, not USB3. To get it to show up on the USB3 bus you have to pull the power from the hub and plug it back in again. It has to be the power , simply pulling the USB plug and putting that back in does not work.
At first it sounds like a bad hub , but the exact same thing was happening with another set of things plugged in before I even got the hub. When I first started up the computer I plugged in an older wired USB Apple keyboard ( the one that has a USB hub built into it) and that seemed to cause ALL other USB devices which were plugged directly into the iMac ( not into the hub of course) to go onto the USB2 bus and not the USB 3 one.
There has to be a link between these two problems.... but they are both slightly different.
iMac, OS X Mountain Lion (10.8.2), 27" 3.4GhZ