Enermax MAXPRO 500w Power Supply Review

by - 5 years ago




Enermax makes some of the best PSUs money can buy, that much is no secret. Only recently we reviewed the Enermax DIGIFANLESS 550W PSU and we honestly think it’s one of the best power supplies we’ve ever tested! It set the bar pretty high and while the unit we’re testing today is a little further down the price ranges, I’m still eager to see if it delivers the same uncompromising performance we’ve seen from Enermax products in the past.

The MAXPRO is designed to be a little more cost-effective, so it strips away the premium packaging, there are no modular cables and it only offers standard 80 Plus efficiency, which doesn’t sound that great, but from what we’ve been told, it makes up for this with rock solid build quality and great performance. Designed for demanding systems, the MAXPRO will run stable & safe 24/7 @ 40c operation, which is certainly better than most. IT comes with all the safety regulations you could hope for, a high-quality 12cm fan for virtually silent operation, it’s Haswell ready and much more.

Enermax Max PRo 500W PSU

As I said before, the packaging is pretty basic, but at the end of the day, a box is just a box and that’s a little extra cost saving for the consumer.


In the box, you’ll find the mains adaptor, a simple user’s manual and some mounting screws; not much, but it’s literally all you’re going to need.



A Closer Look – Exterior

First impressions of the PSU are very positive. The build quality feels great and there’s a good quality powder black paint job that gives it a nice premium finish. On the top, you’ll find a 120mm fan-grille, with one of Enermax’s own 120mm Twister Bearing fans installed behind it. There’s also a sloped edge to the fan housing, which Enermax call AirGuard, this is a patented air-inlet with an “optimal aero-dynamical design” to reduce noisy air turbulence.


On the left and right sides, you’ll find a painted on MAXPRO logo, nothing too fancy, but it certainly looks presentable.


Around the back, a bit of ventilation for heat exhaust, as well as a master power switch and AC line-in.


This is a hard-wired PSU, so all the cables come through a single opening, which has been fitted with a thick plastic grommet to prevent cable damage.


The main specifications can be found on the base of the PSU. What’s good to see is that despite only being 500W, we’ve still got an impressive 38A on the +12V rail, so that should be more than enough to power a high-end graphics card or similar device.



The cables are treated with a fine mesh braided, it’s not the best, but it helps keep them a little tidier within your system. They’re certainly not designed to look great, but they feature sturdy connectors and they’ll certainly get the job done.


You’ll find a 4+4 pin, 24-pin, 2 x 6+2 pin, as well as a good selection of SATA and Molex connectors; more than enough for most mid-tower system.

Enermax Max PRo 500W PSU Cables


A Closer Look – Interior

The interior of the unit is pretty bare, but then again this unit only needs to deliver 500W, so it doesn’t need a lot of hardware. What is surprising is that the PCB doesn’t fill the chassis, perhaps Enermax could have made this unit smaller? Then again, they would have also needed to make the fan smaller, so that’s no doubt the deciding factor for the size.


The main bulk capacitor is a Japanese made part, rated for 400V, 330 uF and 105c.


The main hardware is pretty straight forward and everything is well spaced out, which should help with heat dissipation. There’s also a pair of vertical heat sinks, which should further help with the cooling capabilities.


The AC line filtering stage, which is nicely laid out and a lot tidier looking than most PSU’s, although that’s no doubt partially thanks to the extra space available in this unit.


There’s a mixture of brands for the rest of the caps, as only the main bulk capacitor is advertised as Japanese made. Will this make a big difference to the performance? We’ll find out shortly! Of course, this is a hard-wired unit, so there is a lot of cables here, but they’re neatly laid out and shouldn’t interfere with airflow too much.


All cables have been very neatly soldered and wrapped with shrink tubing on the tips, giving a clean PCB and showing that a good amount of effort has gone into its construction.


The SD122512H-OD fan is one of Enermax’s own twisted bearing fans, with curved “bat wing” blades. These blades will help better direct the airflow and reduce air turbulence for cooler and quieter performance.



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 over multiple virtual rails. As you can see, this PSU performed exceptionally well, with very little deviance from the rated voltages. The 3.3V rail had the most deviation but is still performing very well. Overall, this is on par with what we’ve seen in many very high-end PSUs.

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.



The efficiency isn’t amazing on this unit, as it’s only rated to 80%. However, you can see that it’s actually performing above Bronze and much closer to Silver rating, a pleasant surprise to say the least.

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).


PFC is incredibly good on this unit, below 40% load, it’s about where most PSUs perform, but from 40-80% the unit delivered near perfect performance.



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  3.4  3.6  7.2
40  4.8  4.2  9.4
60  5.4  5  11.4
80  9.2  6  14.6
100  16.4  8.4  28

With the mixture of capacitors and the limited hardware inside this unit, I wasn’t expecting especially impressive results, but the MAXPRO knocked it out of the park here, with very impressive ripple suppression across all load scenarios.

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).


Another impressive result, with the unit showing it was capable of drawing 35%+ more power ran the rated specification before the OPP kicked in and powered down the unit. This is good news, as it means that power spikes when your gaming are unlikely to cause the system to power 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


Pay close attention to the numbers on the left and you’ll notice that the fan speed only has a deviance of 12RPM here. This could be attributed to an error of margin in our testing hardware and it’s easier to say the fan was approximately 730RPM at all time. This is nice and slow and also incredibly quiet; you’re unlikely to ever hear this unit running!


Final Thoughts


I actually got to this part of the review without knowing the price of the Enermax MAXPRO 500W. I knew it would be cheaper thanks to the budget packaging, non-modular design and lower wattage, but I didn’t expect it to be as extremely affordable as it is! You can pick up the MAXPRO 500 from a few reputable retailers, including Lambdatek for just £41.95. Readers in the US may have to check with their own retailer of choice, as we couldn’t find stock at the time of writing outside of the EU.


I’m very impressed with the MAXPRO 500W power supply. If I had to judge it on first looks, I may have dismissed it quite quickly, but the performance figures speak for themselves. The hard-wired cables are hardly visually appealing, they’re about as standard as you could expect from a budget PSU, then there’s the brown box packaging, the low-wattage and the budget price; all these things usually indicate lower performance. Of course, I would have been utterly wrong, as the performance was nothing short of exceptional.

The voltage regulation is fantastic, very tight across the whole range and easily on par with much more expensive units. The ripple suppression is far better than I would have expected, the PFC is very good and even the efficiency performed higher than expected. In short, this PSU far exceeded my expectations and that’s certainly no bad thing. For a unit of this price, it runs reasonably efficient, delivers consistent and clean power, the fan is quiet and it’s so cheap, you would be a fool to look at anything else in this price range for this wattage.

There really is little else to say about this unit, it doesn’t look anything special, it’s certainly affordable, but the performance is superb, making this one of the best budget friendly units on the market!


  • Excellent voltage regulation
  • Good PFC
  • Virtually silent performance
  • Durable build quality
  • High-quality 120mm fan
  • Virtually silent performance
  • Very low ripple
  • Budget friendly


  • Not the most visually appealing unit due to hard-wired cables

“Being on a tight budget no longer means you have to settle for second best. The MAXPRO 500 may look like a cheap PSU, but it’s performance is anything but! This would make a great addition to any system where performance is more important than appearance.”

Enermax MAXPRO 500w Power Supply Review

Enermax MAXPRO 500w Power Supply Review

Thank you Enermax for providing this review sample.

Article Index

  1. Introduction
  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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