I have an Intel NUC D54250WYK running BIOS V32, Ubuntu 14.04 and Unity with a very similar issue. If I boot with the 290e usb tuner attached and then turn on an external DAC, the Cambridge Audio DacMagic 100, all the USB ports fail. Logs show a xHCI host crash.
I found two ways to manage the problem.
1. Uninstall the MythTV backend - undesirable as the 290e is simply not used
2. Remove the 290e usb tuner during booting. Putting it in after a minute after booting means both DAC and 290e coexist. The same hardware works perfectly well on several other machines without this inconvenience.
Same issue here. Xubuntu, Latest LTS release: 14.04, Trusty Tahr
I am using an external DVB USB device which suffers from data loss using the linux xhci driver when streaming on my DN2820 NUC. Using two cards on the same hub even causes the usb stack to crash completely.
A workaround is to disable the first (front) USB port. This forces linux to use the ehci driver which works just fine with the backside USB 2.0 ports.
But of course this is no satisfying solution. While the bug itself might not be intels fault (though I wouldn't bet on that yet even though linux is known for USB 3.0 issues ;-) )
PLEASE RE-ADD the Bios option to disable XHCI in the bios! (Why did you remove it anyway? The more options in the bios, the better...)
p.s. an option to disable USB power in S3 sleep mode (not only S5) would also be highly appreciated...