Here is very telling terse voltage table according to load, ORIGINAL=stock PSU and wiring, NEW=new 12V@30 amp PSU, NEW/12AWG = new 12V@30 amp PSU and changed wiring to 12AWG:
ORIGINAL NEW NEW/12AWG
12.16......12.16....12.16 = No-load voltage at boot
9.85.......11.72....11.94 = Bed only pre-heating
11.13......11.92.....12.1 = Nozzle only pre-heating
9.65.......11.64....11.91 = Hot-end AND Bed pre-heating
Big improvement! The Bed and Hot-end even heat faster, prints have appeared to have been more consistent (I never checked actual voltage at the Bed nor Hot-end during pre-heat). I strongly suggest if you have the stock HICTOP PSU that you upgrade it. Be prepared to tweak you printer calibration after the upgrade. Yes, it does fit the stock HIC i3 power supply mounting plate using the 4 inner screw locations. You will need 4 each 4x5mm screws for mounting, I found some spares in my original HICTOP supplied hardware kit.
Power Supply (PSU), 12 volt 30 amp was purchased here for $23.97 with Amazon prime free shipping, it arrived in 2 days:
Here is the new compared to the original (new is obviously larger):
Here is a bottom view showing 12AWG wire between PSU and the RAMPS control board. I used stick on wire management attached to the rear aluminum rail to hold the cabling.