I have just installed a powered external USB 3 drive on my new Samsung laptop for backup. It randomly disconnects and is no longer recognised when plugged into the USB 3 port. There appear to be no problems using the USB 2 port. Western Digital technical support has basically said it is not their problem (even though a cursory examination of the forum indicates lots of people had problems with USB 3 ports and external drives over the last few years). When I enquire about up-to-date drivers they say contact your motherboard manufacturer. Reading various other postings it does appear to be a power related issue and therefore presumably part of the firmware of the drive. However, it does not appear to relate to drawing power from the USB 3 port or indeed the USB 3 cable. Any suggestions as to what the solution might be would be more than welcome.
Check if you have any USB 3.0 driver updates for the PC, you need to go to the manufacturer website to get them, also install the latest firmware update for the external hard drive if you have one available. See if you can get another PC with USB 3.0 ports to connect the hard drive, that way you can discard which one has the problem.