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Bitfenix Formula Gold 650W PSU Review

Efficiency, Temperature & Noise

Efficiency

Our efficiency testing procedure is detailed here.

Using results from the previous page, we plotted a chart showing the BF650G's efficiency at low loads, and loads from 10 to 110 percent of its maximum-rated capacity.

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The PSU's efficiency is very high under both normal and light loads. Its lack of modular connectors provides an edge over competing offerings with modular cables.

Efficiency At Low Loads

In the following tests, we measure the BF650G'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 #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan SpeedPSU NoisePF/AC Volts
11.191A0.495A0.476A0.196A19.48571.800%480 RPM9.6 dB(A)0.824
12.085V5.043V3.355V5.093V27.138115.37V
22.452A0.990A0.983A0.393A39.91282.345%480 RPM9.6 dB(A)0.922
12.081V5.043V3.355V5.087V48.469115.33V
33.643A1.488A1.459A5.079A59.39485.996%480 RPM9.6 dB(A)0.954
12.077V5.042V3.354V5.079V69.066115.30V
44.904A1.984A1.968A0.789A79.81287.959%480 RPM9.6 dB(A)0.966
12.073V5.041V3.354V5.073V90.738115.28V

The BF650G's efficiency is very high under light loads. Even with 20W, it comes close to 72%-efficient. In the other three tests, it easily passes the 80% mark.

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.

Test #5VSBDC/AC (Watts)EfficiencyPF/AC Volts
10.100A0.51076.119%0.049
5.099V0.670115.33V
20.250A1.27479.130%0.113
5.095V1.610115.37V
30.550A2.79980.270%0.219
5.088V3.487115.38V
41.000A5.07777.928%0.331
5.077V6.515115.38V
51.500A7.59677.772%0.400
5.064V9.767115.37V
62.500A12.59675.529%0.470
5.038V16.677115.36V
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The 5VSB rail is efficient, as is usually the case in CWT's implementations.

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).

Mode12V5V3.3V5VSBWattsPF/AC Volts
Idle12.113V5.045V3.356V5.100V4.6000.272
115.4V
Standby0.0480.004
115.3V
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According to our measurements, phantom power is very low.

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 46°C (114.8°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 46°C (114.8°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 at 30°C (86°F) to 32°C (89.6°F).  

BitFenix's fan profile is very relaxed, as you can see in the graph above. Up through around 390W of load, the PSU generates less than 10 dB(A), and it has to load the +12V rail with more than 530W to make the fan spin at its highest speeds.


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  • Dark Lord of Tech
    Great Review..Thanks!
    Reply
  • turkey3_scratch
    Man this one is great! Thanks for the review, I appreciate the hard work you put into them.
    Reply
  • Lutfij
    Was a great read for the weekend and an interesting one too. Keep up the good work Aris! ;)
    Reply