Is not work: i try 1.0, 1.2, 1.3 1.4 1.5 all the time is the same value is appears on GPU-Z VDDC for 3D mode: 1.1250 (the default value).
Default value
By cons, if on Memory register i put 1.175 or 1.2 on 0x15 value is work. I have 1.175 or 1.2 on GPU-Z VDDI on 3D mode.