I took the day today to disassemble one of my D3, check and clean hashing boards, disconnect all cables, and did an hard reset etc.
Hopefully to see if the other 2 hashing boards stopped being hidden, as just one is shown.
All parts were in perfect condition, nothing burned and all looked like new, and still i can just see 1 hashing board.
Cannot understand if this is a internal defect in the cables or some firmware error.
Forgot to say that i also changed frequency and voltages various times, to the lowest and to the highest, to see if the boards appeared, with no luck
I have the machine working now but just at 2/3 of regular speed.
Any clues would be appreciated
If the cables aren't confirmed working yet, disconnect all but the active board, then swap that cable to one of the inactive boards and see if you still have a working board. If not, it's not the cable, it's the hashing boards and you should contact Bitmain for replacements (test both the "dead" ones to be sure). If so, swap the connection on the control board to a different socket. If not working, it's the control board and you should contact Bitmain or search secondary markets for a replacement board. If still working, it's probably the cable, swap the cable with one of the ones you removed and repeat the above steps, then do the same with the last one.
If everything works fine, before reinstalling the other two boards, test your psu vga connectors by swapping them out in a working hash board.
Also do all of this with the Bitmain firmware reinstalled. Testing hardware at stock settings is always recommended.