I own 3 2-pacs and I'm having trouble getting them all to work at the same time. I have a Saberent HB-U14P usb hub. They all work fine individually, but when plugged into the hub, only 1 or 2 will work at the same time and the other turns zombie. Re-inserting means the other 2 will be disabled and only the re-inserted one will be hashing. Any tips?