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Using results from the previous page, we plotted a chart showing the EDT1250EWT's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.
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This is a highly efficient PSU under both normal and light loads.
Efficiency At Low Loads
In the following tests, we measure the EDT1250EWT'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 #
12V
5V
3.3V
5VSB
DC/AC (Watts)
Efficiency
Fan Speed
PSU Noise
PF/AC Volts
1
1.217A
0.490A
0.484A
0.195A
19.679
68.013%
0 RPM
<6.0 dB(A)
0.822
12.010V
5.064V
3.295V
5.059V
28.934
115.10V
2
2.458A
0.979A
1.000A
0.396A
39.769
80.212%
0 RPM
<6.0 dB(A)
0.909
12.009V
5.062V
3.294V
5.054V
49.580
115.10V
3
3.698A
1.476A
1.513A
5.051A
59.842
85.095%
0 RPM
<6.0 dB(A)
0.938
12.008V
5.062V
3.294V
5.051V
70.324
115.10V
4
4.932A
1.973A
2.001A
0.790A
79.780
87.753%
0 RPM
<6.0 dB(A)
0.955
12.006V
5.062V
3.294V
5.048V
90.914
115.10V
With only 20W load, this PSU's efficiency is below 70%. In the next three tests, however, it passes the 80% mark. Moreover, through all of these tests, the EDT1250EWT operates passively.
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 #
5VSB
DC/AC (Watts)
Efficiency
PF/AC Volts
1
0.102A
0.510
74.128%
0.067
5.015V
0.688
115.04V
2
0.252A
1.262
80.331%
0.146
5.013V
1.571
115.04V
3
0.542A
2.716
81.586%
0.270
5.008V
3.329
115.04V
4
1.002A
5.010
81.503%
0.389
4.999V
6.147
115.05V
5
1.502A
7.493
81.313%
0.456
4.990V
9.215
115.05V
6
3.001A
14.892
80.944%
0.529
4.962V
18.398
115.05V
Image 1 of 2
The 5VSB rail is highly efficient. CWT pays a lot of attention to its design, using modern circuits that facilitate great results.
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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Mode
12V
5V
3.3V
5VSB
Watts
PF/AC Volts
Idle
12.011V
5.062V
3.296V
5.061V
9.057
0.514
115.1V
Standby
0.051
0.005
115.1V
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Vampire power is low in both cases.
Fan RPM, Delta Temperature, And Output Noise
Our mixed noise testing is described in detailhere.
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).
Enermax's semi-passive mode lasts a long time, up to around 690W load. The fan starts to spin at very low RPMs, and its speed increases slowly. As a result, output noise remains low even under very high loads.
Our last graph shows the fan's speed over the PSU's operating range. The same conditions of the above graph apply to our measurements.
