As per the datasheet values below, S3 can be overclocked to 504Ghs and further to 554Ghs.
The stock clock speed is set in between 225M and 250M and voltage per chip lies in between 0.72Vand 0.75V per chip (366W/S3).
When overclocking to 504Ghs it will be consuming around 390W at 250M Clockspeed.
And when overclocking to 554Ghs the clock speed might be 275M and power consumption around  488Watts.
Further overclocking may not be possible, everything lies in finding the sweet spot frequency.
Take a look at DC-DC converters, they are a lot in nos, do you have any idea? Even this new chip consumes lower voltage than S1.

S3 Datasheet Values
Voltage(V) | Hash Rate(GH/s) | Current(A) | Total power(W) | W/GH
0.72                14.18                 10.40             7.49             0.528
0.75                15.75                 12.24             9.18             0.583
0.80                17.33                 15.20            12.16            0.702
0.85                17.33                 20.00            17.00            0.981