I have the same problem, i think it is a firmware fault( i see the same problem after turning off the pc 3-7 times but if i dont have it conneceted to the USB its start every time in rainbow mode),
as i understand there is a problem while starting pc(before windows, my MB can see there is connected a device but the rgb light wont turn on) But what kind of mis communication between controller and MB i dont know, but it is propperly firmwire or some signal that is not supposed to be there-
My termperary solution is write to crosiar, and when i reconnect my usb it work again, and it is not reconnected to another port just the same while pc is off. Or if you can live with rainbow just dont plug it in, i have just triede a force update firmwire but it still not working.
I do to hope they make a update where i can connect both QL and HD or other rgb fans to the same box :D Thougt it was possible and i used a lot of cash just on the new QL white and then i cannot connect them to my other HD :(
Br i will let you know if i find forward solution
