Efficiency of gold rated power supplies - compared on mining rig load. RAIDMAX gold vs EVGA gold

[Archaea]

Which will be the most efficient power supply configuration on two Asic Antminer Z9 mini (stock each is rated at 300 watts - overclocked 70% is 400-450 watts)

A) Raidmax 1000 watt Vampire (Gold Rated) - One PSU powering two Z9 Minis.
B) (2) Raidmax 1000 watt Vampires (Gold Rated) - One Z9 mini per power supply.
C) (2) EVGA G3 850 watt (Gold Rated) - One Z9 mini per power supply.

I have two z9 mini's and 4 power supplies to test. None of the power supplies are over 1 year old. The load will be constant and identical for each test. In each test I let the units run at least one hour to get up to temperature and at the time I took the pictures/reading - the reading was static (within about +-1 watt). The ASICS were mining Equihash - which is the same algorithm and should be the same computational power thus power draw. Overclock settings identical. These tests were all done the same day in my 72* air conditioned basement - so heat should not be a factor.

I'll tell you I was dead wrong on my guess before I tested.


Answer!

Spoiler

C is most efficient by nearly 50 watts

A) Raidmax 1000 watt Vampire (Gold Rated) - One PSU powering two Z9 Minis. = 870 watts
I figured this single power supply would be the most efficient, because I reasoned that you'd lose more electricity in running two power supplies than you'd gain in an efficiency curve mapping.

B) (2) Raidmax 1000 watt Vampires (Gold Rated) - One Z9 mini per power supply. = 855 watts

C) (2) EVGA G3 850 watt (Gold Rated) - One Z9 mini per power supply. = 805 watts.

I did not try one 850 watt EVGA to the two miners because the single Raidmax 1000 watt read ~870 watts with the two units and I didn't want to potentially exceed the EVGA's power supply max threshold for an hour to complete the apples to apples test.

 

[Tsumi]

I'm fairly sure the loss in efficiency due to running multiple PSUs is miniscule and wouldn't outweigh being higher on the efficiency curve. The only static losses you have are the fan and power cable, both of which would be negligible to overall power consumption.