That's jusr beautiful work there, kinda working same as you did through high ratio clocked down and then pushing the multi up, but heck getting way higher volts than 1.428 you have there on my end heck the 4,75Ghz took 1,432 on this box.
Then again I tested on my set pushing voltages even to 1,65v without any cpu features active and hell it still stays under 90c at full linx stress. So, wondering does it even matter what 4,75Ghz is on my equipment.