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Enermax Digifanless 550W Power Supply Review

Load Regulation, Hold-Up Time And Inrush Current

For an in-depth look at our PSU testing and methodology, please check out How We Test Power Supply Units.

Primary Rails And 5VSB Load Regulation

The following charts show the voltage values of the main rails, recorded over a range from 40W to the maximum specified load, and the deviation (in percent) for the same load range. You will also find a chart showing how the 5VSB rail deals with the load we throw at it.

Load Regulation testing is detailed here.

Hold-Up Time

In the following screenshot, the blue line is the mains signal and the yellow line is the Power Good signal. The latter is de-asserted to a low state when any of the +12V, 5V or 3.3V output voltages fall below the under-voltage threshold, or after the mains power has been removed for a sufficiently long time to guarantee that the PSU cannot operate anymore.

Our hold-up time tests are described in detail here.

The hold-up time is significantly higher than the minimum time that the ATX spec sets. The increased capacity of the bulk cap helps make this happen.

Inrush Current

Inrush current or switch-on surge refers to the maximum, instantaneous input current drawn by an electrical device when it is first turned on. Large inrush current can cause the tripping of circuit breakers and fuses, and may also damage switches, relays and bridge rectifiers. As a result, the lower the inrush current of a PSU, the better.

For details on our inrush current testing, please click here.

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Inrush current is at low levels, despite the APFC converter’s bulk cap's significant capacity.

Load Regulation And Efficiency Measurements

The first set of tests reveals the stability of the voltage rails and the PSU's efficiency. The applied load equals (approximately) 10 percent to 105 percent of the maximum load the supply can handle, in increments of 10 percentage points.

We conduct two additional tests. In the first metric, we stress the two minor rails (5V and 3.3V) with a high load while the load at +12V is only 0.10A. This test reveals whether the PSU is Haswell-ready or not. In the second test, we determine the maximum load the +12V rail can handle while the load on the minor rails was minimal.

Test12V5V 3.3V5VSBPowerDC/AC (W)Efficiency (%)TempIn/Out (°C)PF/AC (V)
12.749A1.973A1.946A0.990A54.8083.9942.840.930
12.081V5.069V3.388V5.046V65.2535.87115.0
26.537A2.956A2.924A1.189A109.7589.2945.210.964
12.070V5.065V3.383V5.033V122.9137.59115.0
310.681A3.455A3.430A1.391A164.8690.9447.770.976
12.059V5.062V3.379V5.019V181.2839.28114.9
414.827A3.950A3.908A1.594A219.7591.4749.430.979
12.046V5.058V3.375V5.004V240.2439.87115.0
518.635A4.946A4.893A1.800A274.7591.7051.390.981
12.035V5.054V3.371V4.991V299.6140.64114.9
622.453A5.936A5.879A2.006A329.7391.6154.790.981
12.024V5.050V3.367V4.977V359.9341.66114.8
726.276A6.935A6.869A2.215A384.6991.3457.540.983
12.012V5.045V3.361V4.962V421.1542.08114.8
830.103A7.931A7.862A2.424A439.5990.9960.760.986
12.000V5.039V3.358V4.946V483.1143.04114.7
934.365A8.441A8.377A2.428A494.7090.1765.270.989
11.992V5.036V3.354V4.938V548.6343.52114.7
1038.626A8.941A8.861A2.533A549.6089.7168.920.990
11.972V5.033V3.350V4.928V612.6244.20114.6
1143.251A8.945A8.872A2.538A604.5589.2874.240.991
11.962V5.031V3.347V4.920V677.1344.65114.5
CL10.100A12.007A12.005A0.004A102.4485.8069.570.962
12.078V5.060V3.370V5.061V119.3943.94115.0
CL244.993A1.002A1.003A1.002A551.8390.3572.310.990
11.966V5.052V3.367V4.993V610.7544.13114.6

As you can see from the temperature column, we pushed the PSU to its limits without regard for its passive design. With 45-degree C ambient temperature, air exiting the PSU's top exhaust grill measured almost 70 degrees C! This translates to a 25-degrees delta, which is huge. However, the unit still delivered its full power for prolonged periods of time without any problems. At 45 degrees, we encountered an issue only when we tried to apply full power from standby; the PSU shut down because one of its protections kicked in (most likely the OTP protection, since at lower than 40 degrees the PSU didn't show any symptoms of this problem). Because Enermax does state that 40 degrees C is the max temperature at which this unit can deliver its full power continuously, we won't subtract any performance points for this.

Load regulation was tight on all rails. However, we expected to see even better results since this is a digital platform. In the efficiency section, the PSU cleared the 80 PLUS Platinum requirement under full load with ease. It didn't pass the other two requirements at 20 and 50 percent of its max-rated-capacity load tests though. Then again, Ecova, the company behind the 80 PLUS program, tests at an unrealistic 23 degrees C. We perform our tests around 20 degrees C higher, so it is natural to measure lower efficiency readings since, as the operating temperature increases, efficiency decreases.

ZDPMS Software During Testing

Several screenshots of the ZDPMS software, which were taken during testing, follow. The order of these screenshots is the same as the order of the tests in the table above.

The readings from the ZDPMS are close to the actual test results, though we'd like to see better accuracy, especially in efficiency and voltage values. Either the program or the digital circuit needs some fine-tuning. Since we have seen digital PSUs with very accurate readings in the past, we believe that this can be fixed in the future. Nonetheless, the provided information of the ZDPMS software will satisfy the average user with results within two-percent accuracy.

  • blackmagnum
    If you think buying a mid-range PSU that costs as much as an enthusiast gaming CPU or graphics card, then you have more money than sense.
    Reply
  • PaulBags
    Why'd my commented get deleted? "This is a passively-cooled PSU, so you should install it with the top exhaust grille facing downward." is totally wrong advice, if you don't believe me read the warnings in the picture YOU took.
    Reply
  • Calculatron
    Ironically, I have yet to try an Enermax PSU, although I really like their other products; I have an ETS-T40-TB, a whole myriad of their fans, and the Ostrog Pink case.
    Reply
  • uglyduckling81
    "This is a passively-cooled PSU, so you should install it with the top exhaust grille facing downward. If you don’t follow this advice, hot air will be trapped inside the PSU"

    Hot air rises. If you have the opening facing down you will be trapping hot air inside. Read your own comment "top exhaust". 'Top' means on top, 'exhaust' means expulsion of air not intake.
    The PSU clearly has vents on the back and sides so I think it's a moot point either way but it's clearly a better idea to install it with the top opening facing upwards.
    Reply
  • nukemaster
    15875927 said:
    Why'd my commented get deleted? "This is a passively-cooled PSU, so you should install it with the top exhaust grille facing downward." is totally wrong advice, if you don't believe me read the warnings in the picture YOU took.
    I think your post got lost(forum bug maybe), not removed. I would see if it was removed and it was not.

    I think this would depend on the case you are using to be honest.

    System air will cool it.

    If the power supply is at the top of your system putting its vent up will cause heat to have no place to go in many cases. Power supplies in the bottom of the case would be better served with the power supply vent face up.

    The power supply has software to let you see the temperatures anyway so you can test. Tom's tests in a hotbox so it is not an actual case.
    http://www.tomshardware.com/reviews/how-we-test-psu,4042.html
    Reply
  • Aris_Mp
    guys sorry for this mistake. It is with the fan grill facing upwards and not down. This is how a single word can bring doom!
    Reply
  • Blueberries
    These are solid! I'd take a SeaSonic SS-520FL2 for $140 over this any day, though!
    Reply
  • PaulBags
    These are solid! I'd take a SeaSonic SS-520FL2 for $140 over this any day, though!
    I have the seasonic, I love it. I prefer the modular connector layout on it too, this emermax only offers a few oddly placed plugs by comparison. The cables arn't as good though, and you don't even get enough to populate all the plugs, although it's sufficent for most scenarios for a 520w PSU.

    I'd very much like to see AC cable clips become standard, I've had the ac work loose on me before when I turned a case slightly to plug something in, glad I didn't have anything important up at the time.


    To anyone who _would_ want the enermax over the seasonic I'm genuinely curious as to why. It's always good to learn and/or gain perspective.
    Reply
  • eklipz330
    i just realized my 7 year warranty for my corsair hx750 expires this year QQ
    Reply
  • f-14
    15875927 said:
    Why'd my commented get deleted? "This is a passively-cooled PSU, so you should install it with the top exhaust grille facing downward." is totally wrong advice, if you don't believe me read the warnings in the picture YOU took.
    I think your post got lost(forum bug maybe), not removed. I would see if it was removed and it was not.

    I think this would depend on the case you are using to be honest.

    System air will cool it.

    If the power supply is at the top of your system putting its vent up will cause heat to have no place to go in many cases. Power supplies in the bottom of the case would be better served with the power supply vent face up.

    The power supply has software to let you see the temperatures anyway so you can test. Tom's tests in a hotbox so it is not an actual case.
    http://www.tomshardware.com/reviews/how-we-test-psu,4042.html

    page 2 second set of pictures picture number 5 what does it specifically say? where does hotair go, where does cold air go, in a fanless case your argument is excellent advice on how to waste money and start a fire. if you are running an antec 1200 with all the fans unless this psu is mounted at the top with the vents down and all the other fans are set to intake into the case you are in great shape, however that mitigates the point of having a fanless psu, you go fanless because you don't want there to be any noise, much less a hoover vacuum for a case.

    i haven't read the warranty card, but i am sure it says something about keeping the psu vents facing up when mounted at the bottom of the case, when mounted on the side that would be interesting.

    nice psu, i will keep it in mind for the next time a customer wants a zero or low noise build.

    someday there will be a liquid cooled PSU, i laugh because of water conduction electricity, but where there is a will, there is a way to circumvent conductivity and deal with all that heat i am sure.
    Reply