Please detail what I should disconnect to isolate a single board to try and determine which is giving me the LIBUSB error.
Nearly a week has passed and not one response to my emails to hashfast regarding my faulty units.
Use the latest cgminer and firmware. Run at 550Mhz when troubleshooting.
Take pictures of the original config before you change anything so you can put it back.
The ribbon cable is used to link the chain.
Disconnect all the ribbon cables to isolate a board.
Use two PCIE power cables from the same PSU for an isolated board.
Connect the power cable (white connector) from the board to its PSU, if it is not already.
Connect the USB cable (black connector) to the board, but make sure the thick black wire is closest to the ASIC (red wire farthest from ASIC).
Try running the boards in pairs (sets of two). If that works, add the third back in. Some boards don't like to the be the master (first board in chain) so try boards in different orders.
Can you provide a step by step guide to isolating a board because I dont want to start taking this expensive machine apart to end up being told that it was my fault it now doesnt work.
1 machine simply throws the LIBUSB error from startup the other runs for a minute and then throws 'No valid hashes for 22 seconds, shutting down thread.
Two very expensive machines not working for a week and no response to my emails. I appreciate you have responded here but to be honest expect much more from you. These machines should be on their way back to you to be replaced.