Antec Earthwatts Gold Pro 750W PSU Review

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Efficiency, Temperature & Noise

Efficiency

Our efficiency testing procedure is detailed here.

Using results from the previous page, we plotted a chart showing the EA750G Pro's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.

The PSU's efficiency is decent, but still lower than most of the models we're comparing it to (especially under light loads).

Efficiency At Low Loads

In the following tests, we measure the EA750G Pro's efficiency at loads significantly lower than 10 percent of its maximum capacity (the lowest load the 80 PLUS standard measures). The loads we dialed were 20, 40, 60, and 80W. This is important for representing when a PC is idle, with power-saving features turned on.

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Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan SpeedPSU NoisePF/AC Volts
11.184A0.496A0.479A0.196A19.38567.882%474 RPM9.2 dB(A)0.826
12.078V5.031V3.318V5.104V28.557115.35V
22.445A0.991A0.992A0.392A39.80979.241%474 RPM9.2 dB(A)0.929
12.075V5.041V3.318V5.099V50.238115.32V
33.638A1.484A1.476A5.093A59.30583.483%474 RPM9.2 dB(A)0.959
12.074V5.043V3.317V5.093V71.038115.30V
44.899A1.982A1.988A0.786A79.73285.779%474 RPM9.2 dB(A)0.973
12.073V5.042V3.317V5.088V92.951115.28V

We would like to see over 70% efficiency at 20W load. Under a 40W load, the 80% mark wasn't possible, unfortunately.

5VSB Efficiency

The ATX specification, along with CEC, ErP Lot 3 2014 and ErP Lot 6 2010/2013, states that 5VSB standby supply efficiency should be as high as possible, recommending 75 percent or higher with 550mA, 1A, and 1.5A of load. The PSU should also achieve higher than 75% efficiency at 5VSB under full load, or with 3A if its max current output on this rail is higher than 3A.

We take six measurements: one each at 100, 250, 550, 1000, and 1500mA, and one with the full load the 5VSB rail can handle.

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Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts
10.100A0.51173.000%0.065
5.107V0.700115.27V
20.250A1.27675.772%0.148
5.104V1.684115.27V
30.550A2.80477.118%0.264
5.098V3.636115.27V
41.000A5.08976.954%0.358
5.089V6.613115.26V
51.500A7.61977.170%0.409
5.079V9.873115.26V
63.000A15.12475.662%0.470
5.042V19.989115.25V

The 5VSB rail's efficiency is low. We would like to see Seasonic improve this circuit in the next revision to its Focus platform.

Power Consumption In Idle And Standby

In the table below, you'll find the power consumption and voltage values of all rails (except -12V) when the PSU is idle (powered on, but without any load on its rails), and the power consumption when the PSU is in standby mode (without any load, at 5VSB).

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Mode12V5V3.3V5VSBWattsPF/AC Volts
Idle12.192V5.026V3.319V5.110V7.8290.413
115.4V
Standby0.0480.005
115.3V

Vampire power is low with both voltage inputs.

Fan RPM, Delta Temperature, And Output Noise

Our mixed noise testing is described in detail here.

The first chart below illustrates the cooling fan's speed (in RPM), and the delta between input and output temperature. The results were obtained at 37°C (98.6°F) to 48°C (118.4°F) ambient temperature.   

The next chart shows the cooling fan's speed (again, in RPM) and output noise. We measured acoustics from one meter away, inside a hemi-anechoic chamber. Background noise inside the chamber was below 6 dB(A) during testing (it's actually much lower, but our sound meter’s microphone hits its floor), and the results were obtained with the PSU operating at 37°C (98.6°F) to 48°C (118.4°F) ambient temperature. 

The following graph illustrates the fan's output noise over the PSU's operating range. The same conditions of the above graph apply to our measurements, though the ambient temperature was between 30°C (86°F) to 32°C (89.6°F).  

Passive operation ends when the load exceeds 250W at +12V. Up through 510W on the same rail, the PSU's noise is kept below 30 dB(A). Even in a worst-case scenario, it doesn't exceed 40 dB(A) so long as the ambient temperature doesn't exceed 32°C.


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Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a contributing editor at Tom's Hardware, covering PSUs.