Enermax Revolution SFX 650W Power Supply Review

The small form factor segment has been hot for a while now when it comes to enthusiast PC builders and Enermax is entering the SFX fray today with the Revolution SFX 650W PSU. It touts fanless modes under 30% load, 100% Japanese capacitors, and complete flat flexible cables for easier routing in tight cases.

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Ripple Testing

Since voltage output is not the only concern when it comes to quality DC output we next examined the ripple and regulation characteristics of the Enermax Revolution SFX 650W. We examine these points since unnecessary ripple can cause premature failure of sensitive components in a number of different PC subsystems.

The DC output quality was logged via our digital oscilloscope and the EasyScope II software package. Each divider horizontally represents 2ms while each divider vertically represents 0.05v or 50mv. The ATX specification states that a unit should remain at or below 120mV of ripple and noise on the 12v rail while under 50mV on the 3.3v/5v rails.

Control Test Graphing

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This image is the blank background control test on an unused connector from our SM-8800 during the Enermax Revolution SFX 650W testing. This lets us determine what the background noise looks like during testing. If at any time a trace deviates from this reading that is the noise/ripple being logged by the oscilloscope for that rail. As you can see the trace is flat and shows as a blue line obscuring the axis. If during a test the axis becomes visible but a waveform is hard to discern it is most likely due to the amplitude of the trace being small in relation to our voltage divider.

120v and 100v Input

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Test #1 is equal to approximately 25% of the rated capacity of the Enermax Revolution SFX 650W at 45c. This makes Test #1 equal to 167W by loading the 12v rail to 12a, the 5v rail to 1a, the 3.3v rail to 1a, the +5vsb to 2a, and the -12v to 0.3a. The trace amplitudes for the Revolution SFX 650W are starting off a bit mixed. The 12v rail is a bit noisy as it is peaking at ~20mV of ripple/noise while the 5v rail hits ~15mV and the 3.3v rail hits ~10mV.

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Test #2 is equal to approximately 50% of the rated capacity of the Enermax Revolution SFX 650W at 45c. This makes Test #2 equal to 326W by loading the 12v rail to 24a, the 5v rail to 3a, the 3.3v rail to 2a, the +5vsb to 2a, and the -12v to 0.3a. Test #2 sees the 12v rail moving up slightly to hit ~25mV of ripple/noise while the minor rails are coming in at ~20mV of ripple/noise (5v rail) and ~15mV of ripple/noise (3.3v rail).

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Test #3 is equal to approximately 75% of the rated capacity of Enermax Revolution SFX 650W at 45c. This makes Test #3 equal to 487W by loading the 12v rail to 36a, the 5v rail to 5a, the 3.3v rail to 4a, the +5vsb to 2a, and the -12v to 0.3a. Test #3 sees an interesting mix of results. In this test, the 12v trace amplitude declines to ~20mV while the 3.3v trace amplitude increases to ~20mV. Rounding things out, the 5v trace amplitude holds at ~20mV just as we saw in Test #2.

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Test #4 is equal to approximately 100% of the rated capacity of the Enermax Revolution SFX 650W at 45c. This makes Test #4 equal to 651W by loading the 12v rail to 49a, the 5v rail to 6a, the 3.3v rail to 5a, the +5vsb to 2a, and the -12v to 0.3a. In the final regular test, we see an across the board increase in trace amplitudes by ~5mV resulting in peak values of ~25mV in this test for each rail.

Torture Test

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The Torture Test is equal to approximately 80% of the rated capacity of the Enermax Revolution SFX 650W at 45C. This makes the Torture Test equal to 524W by loading the 12v rail to 38a, the 5v rail to 7a, the 3.3v rail to 5a, the +5vsb to 2a, and the -12v to 0.3a. At the end of the Torture Test, we see the 12v rail has peaked at ~20mV of ripple/noise while the minor rails have posted peak values of ~20mV (5v rail) or ~15mV (3.3v rail).

DC Output Quality Summary

The overall DC output quality of the Enermax Revolution SFX 650W is certainly passing but it is going to need to do a bit better than that for us to think of it as truly great. During testing, we saw the unit start off with values that varied a bit but the peak value was ~20mV of ripple/noise on the 12v rail. From there, the traces would grow (more or less) and peak at ~25mV for all the rails we examined. If we look at these values in absolute terms first we see that the 12v rail is doing very well as ~25mV is less than ~1/4 of the ATX12v specification limit. However, when we look at the minor rails we see that same ~25mV peak value and that represents ~1/2 of the ATX12v specification limit for those rails. Sure, this unit is an SFX unit but this unit doesn't fare too favorably when we look at our two recent 600W SFX units as it is just mixed with the Thermaltake Toughpower SFX 600W and it trails the Corsair SF600. If we look at the 650W units we have been comparing it to as well, we see that it is mixed with the Cyonic AU-650x, trails the VIVO 24K 650W, trails the FSP Hydro G 650W, and almost bests the Thermaltake Toughpower DPS G 650W. This may not seem great but it does paint this unit in a bit better light as this unit was giving at least one unit a real run for its money. In the end then, this unit is passing but we do have to make some allowances for the constraints on it. Let's move on to the see how this all wraps up.