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Efficiency, Temperature & Noise
Our efficiency testing procedure is detailed here.
Using results from the previous page, we plotted a chart showing the SX500-G's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.
Efficiency is pretty high overall, especially under light loads where this PSU takes the lead from every other SFX- and SFX-L-based model we've tested.
Efficiency At Low Loads
In the following tests, we measure the SX500-G'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.
|Test #||12V||5V||3.3V||5VSB||DC/AC (Watts)||Efficiency||Fan Speed||PSU Noise||PF/AC Volts|
|1||1.195A||0.486A||0.473A||0.196A||19.674||72.238%||898 RPM||13.2 dB(A)||0.863|
|2||2.412A||0.980A||0.984A||0.391A||39.765||78.998%||898 RPM||13.2 dB(A)||0.946|
|3||3.635A||1.467A||1.494A||5.071A||59.883||83.500%||898 RPM||13.2 dB(A)||0.962|
|4||4.848A||1.965A||1.974A||0.786A||79.810||85.718%||898 RPM||13.2 dB(A)||0.979|
Under light loads, this platform's efficiency levels are high. Meanwhile, the fan spins slowly, so output noise is kept to 13.2 dB(A).
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.
|Test #||5VSB||DC/AC (Watts)||Efficiency||PF/AC Volts|
The 5VSB rail achieves high efficiency levels. It is nice to see such efficient 5VSB circuits in compact PSUs.
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).
The SX500-G's vampire power is low with 115V input, and at normal levels with 230V.
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 47°C (116.6°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 47°C (116.6°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).
The fan's noise is kept low under light and moderate loads. You have to apply more than 330W on the +12V rail to get the fan spinning faster, at which point its noise hits the 30-35 dB(A) range. Remember that this is an SFX PSU with high capacity, so you shouldn't expect silent operation, particularly under high loads.
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Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.
I'm afraid I can't find ETA-B and LAMBDA B- ratings in cybenetics sites.Reply
there has been a change/refresh on the ratings. There is no more B, C, D ratings in the new ratings. The thresholds/ranges are exactly the same, just the naming scheme has been changed in some of the ratings. If you go to the ETA and LAMBDA pages you will find the new ratings.Reply
Good write up Aris! Should I revive my SFF system build, I'll know what to shoot for amongst a plethora of STX PUS's.Reply