(K)Ubuntu 15.04 release- problem persists for me also. As I mentioned earlier,
the two always power on USB 3 ports work OK. USB3 devices are not recognised
on the other four ports.
I have to assume the hardware OK because when booting into Windows, the all USB
3 ports/ devices behave
I have more or less come up against this issue as well, with one exception;
two of the USB 3 ports on my Asrock FM2 AMD mobo are powered when the PC is
off, i.e. to charge devices when the PC is not running. Ubuntu 14.04 LTS
detects external USB3 HDD devices when they are plugged into these
