My multi meter reads 8.1 ampere when I tap its output current, so when I multiply by the 220 V voltage, I get 1782 Watt. However, the result is distorted by the electrical magnetic noise around the probe, which is located in the output of voltage regulator. There is a reading discrepancy between probing with 1 machine running and multiple machines with 1 ampere difference or 220 Watt, whereas the lone running machine reads smaller power draw compare to run with multi ones, hence I conclude that the result is distorted by noise.

So assume 1782 watt without distortion is resulting 1782 watt - 220 watt = 1562 watt. Suppose there is 20% power waste with 80% PSU efficiency, the machine power draw without the waste would be 1562 watt / 1.2 = around 1301 watt that makes around 100 watt per GPU, which is ok.