Enermax DIGIFANLESS 550W Power Supply Review

by - 7 years ago


Introduction & Packaging


The latest Enermax power supply landed in the eTeknix officer recently and while I admit, it can sometimes be difficult to get excited about a power supply, I am very much so about this one. The DIGIFANLESS packs two important features, as the name would suggest; it’s fanless and it is digital. Fanless power supplies are an incredible addition to your system, especially if you’re trying to build a completely silent rig, as the removal of the fan means you’ll never hear a single noise from the unit and that’s certainly no bad thing!


Despite being passively cooled, the DIGIFANLESS still promises to churn out two very impressive figures. The first is that it’ll run up to 550W, which is more than enough for a single GPU system and a powerful CPU. The second is that it will deliver 80 Plus Platinum rated levels of efficiency. Let’s just recap, digital monitoring, passive cooled silent performance, 80 Plus Platinum, 550W of power and if that’s not enough to open your eyes wide, he’s the classic “but that’s not all” sales pitch. It also has fully modular, has individually braided premium grade cables, all Japanese capacitors, is rated to run 24/7 and comes with a 5-year warranty! Enough dancing around, let’s jump right in and take a closer look!

The packaging is really nicely designed, giving a good rundown of the specifications and I’m already getting a nice “premium” vibe here.


Around the back, a nice run down of all the cables, the digi features, the high-quality capacitors and more.


Normally the packaging isn’t something I talk about too much, but the DIGIFANLESS was so well packaged, I just had to take a quick picture.


In the box, you’ll find the mains power cable, the digital link cable, the owner’s manual and a protective storage bag.



A Closer Look – Exterior

Power Supply Unit

First thing we see, it a warning about mounting the PSU vent upwards; since this is passive cooled, airflow is very important.


The ventilation on top is plentiful, with a really nice cover that gives it a nice two-tone effect.


There’s a little extra ventilation on the top edges, as well as further ventilation down the left and right side of the PSU.


Even more ventilation around the back, as well as the master power switch and standard 3-pin connector.


Here we can see the connectors for the modular cables, as well as the digital cable. There’s not a huge range of connectors, but more than enough for most single GPU systems with a few hard drives; so most mini-ITX/Micro-ATX systems.


On the base, we can see the power ratings for this unit, with an impressive 30A on the 12V rails, which is again more than enough to power any high-end graphics cards these days.


This is really impressive, the modular cables are all individually sleeved with a black glossy braiding that just oozes premium quality. Even the connectors are the best I’ve ever seen on a power supply an I love the deep red plastics on the GPU power cables.


The 24 pin and 4+4 pin are also braided and are of a good length, ensuring great compatibility with a wide range of chassis’.



A Closer Look – Interior

The top cover is a single piece with loads of ventilation, it was also one of the easier units to open, not that you should of course.

The interior is extremely tidy, which is going to help in a big way with the passive airflow throughout the PSU.  There are very few cables trailing around compared to most active cooled PSUs.


The main bulk capacitor is rated for 400v at 470 uF up to 105c, which is perfect for a unit of this size.


There’s a small PCB here, which looks like it has a fan connector, but it’s most likely for the DIGI monitoring systems, as it’s connected to the output ports at the back.


One thing that really stands out is how tidy the soldering is here. A lot of PSUs have excess solder and lots of glue applied to cover things, but the DIGIFANLESS is neat and tidy; you can tell it has been made with care and precision.


There’s a range of thick and high-quality heatsinks throughout, obviously these are important given the passive design.


The line-in and EM filtering, as well as the main PCB fuse.



Test Procedure

At eTeknix we take the power supply testing procedure very seriously and have invested a lot of resources into acquiring the appropriate testing equipment. For all power supply reviews we test the power supplies with dedicated power supply testing equipment. This means we are able to get the most accurate results from our testing as opposed to using software benchmarks (such as OCCT) or multi-meter readouts which are broadly inaccurate.


Our test machinery is as follows:

  • Sunmoon SM-5500ATE Active Load Tester (1200W rated)
  • Stingray DS1M12 USB Oscilloscope
  • Voltcraft DT-10L laser tachometer

The eTeknix test procedure involves:

  • Testing each power supply at 20/40/60/80/100% load (with balanced load across all rails) and measuring PFC (power factor correction), efficiency (actual power divided by power “pulled at the wall”) and voltage regulation (deviance from expected voltages of 3.3/5/12 on the main rails).
  • Measuring ripple with an oscilloscope at 20/40/60/80/100% load.
  • Measuring fan speed after a stabilisation period of five minutes at each load scenario using the Voltcraft DT-10L laser tachometer and a reflective strip on the fan.
  • Testing each power supply’s OPP (Over Power Protection) mechanism and seeing how many watts each power supply can deliver before shutting down

Other things to consider are that

  • We recognise that a single yellow 12 volt cable can provide only 6 Amps before overheating (which corrupts voltage regulation and efficiency) and so we used an adequate number of cables for each power supply to ensure there is not efficiency loss from poor cables selection
  • Our Sunmoon SM-5500ATE power supply tester is not capable of testing more than 300W on each of the 12 volt rails so where a power supply provides more than 300W on a 12 volt rail that power is distributed over multiple 12 volt rails on the load tester. For example a power supply with one 12 volt rail supplying 750 watts would be spread equally over three 12 volt rails on the load tester, a power supply with two 450W 12v rails would be spread over four 12v rails on the load tester, two 225W 12v rails for each of the 12v rails on the unit.
  • We use the same time scale and horizontal millivolt scale on our oscilloscope for all ripple tests, that is a 20ms T/DIV (horizontal) and a 0.02 V/DIV (vertical) meaning the scale is from -80mV to +80mV, ATX spec dictates that the 12v rail must fall within 150mv of ripple and the 3.3/5 within 50mv so that scale allows us to include both 150 and 50mV peaks. (Some older PSU reviews use different scales which were later ditched as the visual representation they give is inadequate, in these reviews written measurements are provided only).
  • Deviance is the terminology used to represent the way voltages diverge from the expected values

Efficiency, PFC and Voltage Regulation

Voltage Regulation

To test voltage regulation we load the power supply to five different load scenarios that give an equal spread of load across every single rail. So that means 20% on all rails, 40% on all rails and so on. We then calculate the average deviance of each rail from its expected voltage.


Due to the limitations of our load tester, we had to split the 12v rail across multiple “simulated” rails. The results are pretty good overall, with just the 5VSB drooping a little, but still within a safe margin.

Power Efficiency

Power efficiency is measured by calculating actual supplied wattage divided by the wattage drawn at the wall/plug, multiplied by 100 to give a percentage. We then compare that to the particular 80 Plus certification the company claims to see if it meets that. You can see the 80 Plus certifications below, we always test 230v power supplies.



Power efficiency is excellent, and it’s right on the money for an 80 Plus Platinum rated unit.

Power Factor Correction

Power Factor Correction is the ratio of the real power flowing to the load, to the apparent power in the circuit. The aim of PFC is to make the load circuitry that is power factor corrected appear purely resistive (apparent power equal to real power). In this case, the voltage and current are in phase and the reactive power consumption is zero. The closer the number to one the better as this allows the most efficient delivery of electrical power (Source – Wikipedia).


PFS is nice and consistent and another good indication of this being a premium quality product.



Noise and Ripple can easily be measured by an oscilloscope. These show how much voltage fluctuation there is on a particular rail. We tested the rail stability of the 3.3 volt, 5 volt and 12 volt rails using an identical time and millivolt scale for all graphs. millivolt ripple is measured by the peak to peak size of the voltage curve.


Sample Ripple Graph

The latest ATX 12 volt version 2.3 specifications state that ripple from peak to peak must be no higher than 50 millivolts for the 3.3 volt and 5 volt rails, while the 12 volt rail is allowed up to 120 millivolts peak to peak to stay within specifications. Millivolt figures are stated to the closest increment of 5 given their variability.

Load (%) 3.3V Ripple 5V Ripple 12V Ripple
20  5.8  5.03  17.6
40  6  10.2  19.8
60  7  11  18.8
80  7.8  11.8  19.8
100  8.2  13  21.8

Ripple performance is spectacular, you really couldn’t hope for it to perform much better than this and it’s actually better than most PSUs we’ve ever tested!

3.3 volt @ 100%


5 volt @ 100%


12 volt @ 100%



Over Power Protection and Max Wattage

Power supplies often quote as having various protection mechanisms such and the most important of these is Over Power Protection. In our testing we crank up the power draw until the power supply either shuts down (meaning the OPP mechanism is present and working) or blows up (meaning it is either not present or not working). We then note the maximum power consumption before the power supply shut down (or blew up).


550W may not sound like much, but it’s more than enough for most systems. However, should you get any power spikes, you can take comfort that it’ll handle up to 730.3W before powering down.


Fan Speed

When testing in a power supply laboratory it is difficult to take fan noise readings as the noise from the Sunmoon test equipment and air conditioning corrupts everything. The next best thing in our circumstances was reading off the fan speed with a tachometer to get an idea for the noise. The ambient temperature during testing held constant at 22 degrees, with 1 degree of variation. Each power supply had a consistent time period of 5 minutes to stabilise between each load scenario. 

In my experience the following general relationships apply between noise levels and fan speeds, though it can vary greatly between the type of fan used.

  • Below 800 RPM – Inaudible/Silent
  • 800 to 1000 RPM – Barely audible
  • 1000 – 1200 RPM – Audible but still quiet
  • 1200 – 1400 RPM – Moderately noisy
  • 1400 – 1800 RPM – Noisy
  • 1800 RPM or higher – Intolerable

I think we all know why there is no graph here! It doesn’t have a fan, it was 0dBa throughout all our tests, that pretty much sums itself up nicely, don’t you think?


Final Thoughts


The Enermax DIGIFANLESS 550W Modular Power Supply is a premium quality product, so it does command a premium price tag. At £179.99 it’s going to hurt your wallet, but that’s the premium you need to pay for high levels of efficiency, design and silent performance.


As I was saying at the start of this review, it’s rare I find a PSU particularly exciting. Of course, I love a good quality unit as much as the next person, but it was immediately apparent that the DIGIFANLESS was something truly special. From the moment I took it out of the box, right up until the moment I packed it all away, I knew this was a great power supply and after reading this review and seeing our testing results, I’m sure you’ll agree with me on this.

The build quality is as good as it gets. There’s a fantastic design that will look great in virtually any system, from the premium quality finish on the exterior and even the interior of the unit, right down to the cables, their connectors and heck, even the box was nicely designed and the contents were packed with love and care. When you’re paying such a premium price, you expect a premium experience and I certainly found one here.

The braided cables put this unit a cut above the competition, I’ve seen pro modded cables on a lot of units and the ones provided here by Enermax are easily on par with those. If you want your system build to look extra special, these cables will help you greatly and it’s a welcome break from the common cables we see, even on many high-end units.

The passive cooling is a blessing, with perfectly silent, coil whine free performance no matter how much strain we put this unit under. Right up to full load and beyond, we never heard a peep from this unit and that’s a great thing for those planning a completely silent system build.


  • Fully modular cables
  • Excellent ripple suppression
  • Completely silent
  • Braided cables with high-quality connectors
  • Gorgeous aesthetics
  • Great performance
  • Platinum-rated efficiency
  • Trusted brand name


  • None


  • It is expensive, but you really do get a lot in return for your investment

“The Enermax DIGIMAXFANLESS is without a doubt one of the best power supplies we’ve ever tested. It’s completely silent, looks superb, comes with braided cables and more. The perfect addition to any single-GPU system.”

Enermax DIGIFANLESS 550W Power Supply Review

Enermax DIGIFANLESS 550W Power Supply Review

Thank you Enermax for providing this review sample.

Article Index

  1. Introduction and Packaging
  2. A Closer Look - Exterior
  3. A Closer Look - Interior
  4. Test Procedure
  5. Efficiency, PFC and Voltage Regulation
  6. Ripple Testing
  7. OPP and Max Wattage
  8. Fan Speed
  9. Final Thoughts
  10. View All

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