I've had this problem since day one with my Rift/PC, but have only really been in need of an extension after a recent move. I am using not only the insignia cable, but have also tried it with several brands of USB 3.0 extensions and HDMI extension cables. None of them have been above 7 feet. When connected directly, the Rift works great, and likewise when I connect the HDMI directly (without an extension), but use one of the USB extensions, it also works great. It seems to have something to do with the HDMI but I honestly don't know what. I've included my Oculus logs from about a minute of running it with an extension cable connected. Oculus Home currently lists my rift as connected with a USB 3.0 connection.