its not a ref PCB, it is one of the two custom PCB's which retain the ability to change voltage. The other being the ASUS DirectCU version, which I have. I believe that your card is just borked... but in general my feel is that these custom PCB are just not very good with voltage... it takes me well over stock voltages (its at 1.1813) to reach anything above 830... whereas reference PCBs can easily achieve 850+ on stock voltages alone.

Sigh, I would ask them to issue an RMA because their advertised voltage control does not work to some extent...because it is a selling point to that card! Good luck!