I am in the process of setting up a MacPro whose sole purpose is to run VMs on each of the six possible screens each with it's own keyboard and mouse. So what I have is six DVI monitors with six dual-link display-port to DVI/USB adapters and an Anker 10 port USB hub/charger to power them all. The VMs are to be each assigned their own keyboard through virtualbox USB filters.
Originally the monitors were having some trouble coming up all at once (and in order) with a Macally 7 port hub so I'd thought the issue was the amount of power the hub was outputting. Additionally none of the keyboards except for the one attached directly to the MacPro itself were being recognized so more power was figured necessary.
However even with the more powerful Anker USB Hub the system will not work with the extra keyboard and mouse attached through the hub with a single monitor running. The "USB Needs more power." message still comes up. These all happened to be old extra Apple keyboards. I've also tried with a couple of non-Apple specific keyboards and it appears that they only work when hooked up directly to the MacPro even though the USB power message does not come up. Next I'll be trying separate hubs for the display port hookups and the keyboards and mice to see if it is some sort of weird dual-link display-port to dvi issue.
Will MacPros only recognize a single Apple Keyboard? Only keyboards hooked up directly? Is this by chance a software issue I can disable or work around with extra software?