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Enermax Digifanless 550W Power Supply Review

Transient Response Tests

In these tests, we monitor the response of the PSU in two different scenarios. First, a transient load (10A at +12V, 5A at 5V, 5A at 3.3V and 0.5A at 5VSB) is applied to the PSU for 200ms while the PSU is working at 20-percent load. In the second scenario, the PSU is hit by the same transient load while operating at 50-percent load. In both tests, we use our oscilloscope to measure the voltage drops caused by the transient load. The voltages should remain within the ATX specification's regulation limits.

These tests are crucial since they simulate the transient loads a PSU is likely to handle (such as booting a RAID array or an instant 100-percent load of CPU/GPUs). We call these tests "Advanced Transient Response Tests," and they are designed to be tough to master, especially for a PSU with a capacity below 500W.   

For details on our transient response testing, please click here.

Advanced Transient Response at 20 Percent

VoltageBeforeAfterChangePass/Fail
12V12.072V11.954V0.98%Pass
5V5.073V4.999V1.46%Pass
3.3V3.384V3.278V3.13%Pass
5VSB5.028V4.964V1.27%Pass

Advanced Transient Response at 50 Percent

VoltageBeforeAfterChangePass/Fail
12V12.034V11.962V0.60%Pass
5V5.057V4.978V1.56%Pass
3.3V3.372V3.263V3.23%Pass
5VSB4.989V4.919V1.40%Pass

The Enermax unit responded well to our Advanced Transient Response tests, registering low deviations on all rails. The only one that didn't fare well against the competition was the 5VSB rail. However, with a two-percent deviation, this is still a decent result.

Below are the oscilloscope screenshots we took during Advanced Transient Response testing.

Transient Response At 20-Percent Load

Transient Response At 50-Percent Load

Turn-On Transient Tests

We measure the response of the PSU in simpler scenarios of transient load—during the PSU's power-on phase—in the next set of tests. For the first measurement, we turn the PSU off, dial the maximum current the 5VSB can output and then switch on the PSU. In the second test, we dial the maximum load +12V can handle and start the PSU while it's in standby mode. In the last test, while the PSU is switched off (we cut off power or switch the PSU off by flipping the on/off switch), we dial the maximum load the +12V rail can handle before switching the PSU on from the loader and restoring power. The ATX specification states that recorded spikes on all rails should not exceed 10 percent of their nominal values (+10 percent for 12V is 13.2V and 5.5V for 5V).    

We noticed a small voltage overshoot on the 5VSB rail, but it was much lower (5.2 V) than the ATX specification's upper limit. On the +12V rail we measured small spikes, which are nothing to worry about since they are barely noticeable.

  • 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