Introduction

The Enermax PRO87+ and MODU87+ are two series of power supplies with 80 Plus Gold certification. The two series are internally identical, and the one difference between them is the use of a modular cabling system on the MODU87+ models. We’ve already reviewed the MODU87+ 700 W power supply, which achieved terrific performance in our tests. Let’s see if the PRO87+ 500 W follows the same steps.

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Figure 1: Enermax PRO87+ 500 W power supply

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Figure 2: Enermax PRO87+ 500 W power supply

The Enermax PRO87+ 500 W is 6.3” (160 mm) deep, using a 140 mm, twister bearing fan on its bottom, model EA142512W-OAB. This fan keeps spinning for at least 30 seconds after you turn off the power supply, in order to cool down the power supply components and provide a higher life span.

This unit features active PFC, of course.

As explained, it doesn’t come with a modular cabling system. The cables included are the following:

• Main motherboard cable with a 24-pin connector, 22.8” (58 cm) long
• One cable with two ATX12V connectors that together form an EPS12V connector, 23.2” (59 cm) long
• Two cables, each with one six/eight-pin connector for video cards, 18.5” (47 cm) long
• One cable with four SATA power connectors, 16.9” (43 cm) to the first connector, 5.5” (14 cm) between connectors
• One cable with two SATA power connectors and two peripheral power connectors, 16.9” (43 cm) to the first connector, 5.5” (14 cm) between connectors
• One cable with three standard peripheral power connectors and one floppy disk drive power connector, 16.9” (43 cm) to the first connector, 5.5” (14 cm) between connectors

All wires are 18 AWG, except the wires in the main motherboard cable, which are all thicker (16 AWG).

The cable configuration is perfect for a 500 W power supply.

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Figure 3: Cables

Let’s now take an in-depth look inside this power supply.

A Look Inside The Enermax PRO87+ 500 W

We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works and to compare this power supply to others.

On this page we will have an overall look, while in the following pages we will discuss the quality and ratings of the components used in detail. The printed circuit board of the PRO87+ 500 W is identical to the one used in the MODU87+ 700 W model, so we were curious to see what components were changed.

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Figure 4: Top view

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Figure 5: Front quarter view

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Figure 6: Rear quarter view

Transient Filtering Stage

As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil. 

In this power supply, this stage is flawless. It has two Y capacitors and one coil more than the minimum required, plus one X capacitor after the rectifying bridge.

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Figure 7: Transient filtering stage (part 1)

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Figure 8: Transient filtering stage (part 2)

In the next page we will have a more detailed discussion of the components used in the Enermax PRO87+ 500 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of the Enermax PRO87+ 500 W For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU8J rectifying bridge on its primary, which is attached to an individual heatsink. This component supports up to 8 A at 100º C, so in theory, you would be able to pull up to 920 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 736  without burning itself. Of course, we are only talking about this component, and the real limit will depend on all the other components in this power supply. The MODU87+ 700 W uses one 20 A bridge here.

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Figure 9: Rectifying bridge

The active PFC circuit uses two SiHG20N50C MOSFETs, each one capable of delivering up to 20 A at 25º C or up to 11 A at 100º C (note the difference temperature makes) in continuous mode, or up to 80 A in pulse mode at 25º C. These transistors present a 225 mΩ resistance when turned on, a characteristic called RDS(on). The lower this number the better, meaning that the transistors will waste less power and the power supply will have a higher efficiency. The MODU87+ 700 W uses different transistors here, but with similar specs.

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Figure 10: Active PFC transistors and diode

The active PFC circuit is controlled by a CM6502 PFC controller.

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Figure 11: Active PFC controller

The output of the active PFC circuit is filtered by one Japanese electrolytic capacitor, from Matsushita (Panasonic), labeled at 85º C.

In the switching section, two 2SK4107 power MOSFETs are used. They are capable of handling up to 15 A at 25º C in continuous mode, or up to 60 A at 25º C in pulse mode, with an RDS(on) of 330 mΩ. Unfortunately the manufacturer doesn’t say the maximum current at 100º C. The MODU87+ 700 W uses more powerful transistors here.

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Figure 12: Switching transistors

The switching transistors are connected using a design called “LLC resonant,” also known as a series parallel resonant converter, being controlled by a CM6901 integrated circuit, which operates under PWM (Pulse Width Modulation) mode when the power supply is operating under light load but under FM (Frequency Modulation) mode under other loads.

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Figure 13: Controller

Let’s now take a look at the secondary of this power supply.

Secondary Analysis

This power supply uses a synchronous design on its secondary, meaning that the Schottky rectifiers were replaced by MOSFET transistors in order to increase efficiency. On top of that, this unit uses a DC-DC design, meaning that this unit is basically a +12 V power supply, with the +5 V and +3.3 V outputs being generated by two small power supplies attached to the +12 V output.

The +12 V output is produced by four IRFB3206 MOSFETs, two for the direct rectification and two for the “freewheeling” part of the rectification. Each transistor has a maximum RDS(on) of only 2.5 mΩ and can deliver up to 270 A at 25º C or up to 190 A at 100º C in continuous mode, or up to 1,080 A at 25º C in pulse mode. Good Lord! This would give us a maximum theoretical current of 266 A for the whole +12 V bus; if all this current would be pulled from the +12 V outputs, this unit would be able to deliver up to 3,192 W! Of course other parts of this power supply would burn way before we could be even close to this theoretical value. These are the same transistors used in the MODU87+ 700 W.

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Figure 14: Transistors of the +12 V rail

The +5 V and +3.3 V outputs are generated by two small power supplies available on small daughter boards attached to the +12 V rail. Each of these power supplies is comprised of three APM2556 MOSFETs and one APW7073 PWM controller.

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Figure 15: One of the DC-DC converters

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Figure 16: One of the DC-DC converters

This power supply uses a PS231 monitoring integrated circuit, which supports over voltage (OVP), under voltage (UVP) and over current (OCP) protections. The over current protection circuit available in this integrated circuit has five channels, one for +3.3 V, one for +5 V, and three for +12 V. This matches the number of +12 V rails advertised by the manufacturer.

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Figure 17: Monitoring circuit

The electrolytic capacitors available in the secondary are from also Japanese, from Chemi-Con, and labeled at 105º C. The secondary also has some solid capacitors.

Power Distribution

In Figure 18, you can see the power supply label containing all the power specs.

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Figure 18: Power supply label

According to the label the power supply has three +12 V rails, and we can confirm that this unit really has three +12 V rails, as explained in the previous page. These rails are divided like this:

• +12V1 (solid yellow wires): ATX12V/EPS12V connectors and motherboard main cable
• +12V2 (yellow/black wires): SATA connectors, peripheral connectors (the ones available on the same cable as the SATA connectors), and one of the video card power connectors
• +12V3 (yellow/blue wires): Peripheral connectors and one of the video card power connectors

This distribution is perfect, as it separates the CPU and each video card power connector on individual rails.

Let’s now see if this power supply can really deliver 500 W.

Load Tests

We conducted several tests with this power supply, as described in the article Hardware Secrets Power Supply Test Methodology.  

First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching the behavior of the reviewed unit under each load. In the table below, we list the load patterns we used and the results for each load.

If you add all the powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (e.g., the +5 V output working at 5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.

The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During this test the +12VA input was connected to the power supply +12V1 and +12V3 rails, while the +12VB input was connected to the power supply +12V2 rail.

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	4 A (48 W)	7.5 A (90 W)	11 A (132 W)	14 A (168 W)	17.5 A (210 W)
+12VB	3 A (36 W)	7 A (84 W)	10.5 A (126 W)	14 A (168 W)	17.5 A (210 W)
+5V	1 A (5 W)	2 A (10 W)	4 A (20 W)	6 A (30 W)	8 A (40 W)
+3.3 V	1 A (3.3 W)	2 A (6.6 W)	4 A (13.2 W)	6 A (19.8 W)	8 A (26.4 W)
+5VSB	1 A (5 W)	1 A (5 W)	1.5 A (7.5 W)	2 A (10 W)	2.5 A (12.5 W)
-12 V	0.5 A (6 W)	0.5 A (6 W)	0.5 A (6 W)	0.5 A (6 W)	0.5 A (6 W)
Total	104.6 W	204.1 W	307.6 W	404.7 W	502.6 W
% Max Load	20.9%	40.8%	61.5%	80.9%	100.5%
Room Temp.	45.9º C	44.6º C	44.7º C	46.3º C	45.0º C
PSU Temp.	50.5º C	49.5º C	49.4º C	51.2º C	49.3º C
Voltage Stability	Pass	Pass	Pass	Pass	Pass
Ripple and Noise	Pass	Pass	Pass	Pass	Pass
AC Power	118.4 W	224.8 W	344.6 W	458.2 W	581.4 W
Efficiency	88.3%	90.8%	89.3%	88.3%	86.4%
AC Voltage	114.5 V	114.3 V	343.8 V	110.2 V	110.2 V
Power Factor	0.984	0.986	0.994	0.996	0.997
Final Result	Pass	Pass	Pass	Pass	Pass

The Enermax PRO87+ 500 W can really deliver its labeled wattage at high temperatures.

Efficiency was always very high, between 88.3% and 90.8% when we pulled between 20% and 80% of the labeled wattage (i.e., between 100 W and 400 W). At full load (500 W) efficiency dropped to 86.4%, still a very high efficiency. Being an 80 Plus Gold unit, this power supply should deliver 87% efficiency at full load. However, as we always explain, tests performed by 80 Plus are done at a room temperature of only 23º C, while this particular power supply we tested at almost 50º C at full load, and efficiency drops with temperature.

Voltages were always inside the allowed range.

Noise and ripple were always extremely low, except on -12 V output, which peaked 119.8 mV during test five. Below you can see the results for the power supply outputs during test number five. The maximum allowed is 120 mV for +12 V and -12 V, and 50 mV for +5 V and +3.3 V. All values are peak-to-peak figures.

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Figure 19: +12VA input from load tester during test five at 502.6 W (26.2 mV)

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Figure 20: +12VB input from load tester during test five at 502.6 W (26.2 mV)

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Figure 21: +5V rail during test five at 502.6 W (22.2 mV)

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Figure 22: +3.3 V rail during test five at 502.6 W (20.8 mV)

Let’s see if we can pull even more from the Enermax PRO87+ 500 W.

Overload Tests

Below you can see the maximum we could pull from this power supply. If we tried to increase one amp at any given output, the unit would shut down, showing that one of its protections kicked in, which is always the desired behavior. During this test, the noise level at -12 V output was a little bit above the maximum allowed (122.4 mV), but noise levels at all other outputs were still very low, and all voltages (except -12 V) was still inside a tighter 3% voltage regulation.

Input	Overload Test
+12VA	24 A (288 W)
+12VB	24 A (288 W)
+5V	10 A (50 W)
+3.3 V	10 A (33 W)
+5VSB	2.5 A (30 W)
-12 V	0.5 A (6 W)
Total	676.4 W
% Max Load	135.3%
Room Temp.	50.1º C
PSU Temp.	53.9º C
AC Power	808 W
Efficiency	83.7%
AC Voltage	108.1 V
Power Factor	0.998

Main Specifications

The specs of the Enermax PRO87+ 500 W include:

• Nominal labeled power: 500 W continuous at 50º C, 550 W peak
• Measured maximum power: 676.4 W at 50.1º C ambient
• Labeled efficiency: Between 87% and 92% at 230 V, 80 Plus Gold certification
• Measured efficiency: Between 86.4% and 90.8% at 115 V (nominal, see complete results for actual voltage)
• Active PFC: Yes
• Modular Cabling System: No
• Motherboard Power Connectors: One 24-pin connector and two ATX12 V connectors that together form an EPS12V connector
• Video Card Power Connectors: Two six/eight-pin on separate cables
• SATA Power Connectors: Six on two cables
• Peripheral Power Connectors: Five on two cables
• Floppy Disk Drive Power Connectors: One
• Protections: Over voltage (OVP), under voltage (UVP), over current (OCP), over power (OPP), over temperature (OTP), and short-circuit (SCP) protections
• Warranty: Five years
• More Information: http://www.enermaxusa.com
• Average price in the US*: USD 140.00

* Researched at Newegg.com on the day we published this review.

Conclusions

The performance of the Enermax PRO87+ 500 W is terrific, with efficiency peaking 90.8% at 115 V, extremely low noise and ripple levels, and voltages always within the allowed range. The cable configuration is perfect for a 500 W product.

The only negative point we can see is its price (USD 140), even though so far we haven’t tested any 500 W power supply that could achieve practically 91% efficiency. This unit is, therefore, targeted to users that demand only the best in class. The average user, however, will find a better value in less expensive products.