Introduction

So far, there are four models within Corsair’s new HX power supply series with the 80 Plus certification: 650 W, 750 W, 850 W, and 1,050 W. We’ve already reviewed the 850 W model, which received our “Golden Award.” Let’s see if the 650 W model is also a good buy.

The 850 W model is manufactured by CWT; however, the 650 W model is manufactured by Seasonic, based on the G-650 model from this manufacturer. Therefore, they use a completely different internal design.

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Figure 1: Corsair HX650 Gold power supply

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Figure 2: Corsair HX650 Gold power supply

The Corsair HX650 Gold is 6.3” (160 mm) deep. It uses a 140 mm ball-bearing fan on its bottom (Yate Loon D14BH-12).

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Figure 3: Fan

This power supply has a partial modular cabling system, with six connectors: two for video card connectors and four for peripheral and SATA connectors. This power supply comes with the following cables:

• Main motherboard cable with a 20/24-pin connector, 23.6” (60 cm) long, permanently attached to the power supply
• One cable with two ATX12V connectors that together form an EPS12V connector, 25.6” (65 cm) long
• Two cables, each with one six/eight-pin connector for video cards, 23.6” (60 cm) long, modular cabling system
• One cable with four SATA power connectors, 21.6” (55 cm) to the first connector, 3.9” (10 cm) between connectors, modular cabling system
• One cable with four SATA power connectors, 16.1” (41 cm) to the first connector, 3.9” (10 cm) between connectors, modular cabling system
• Two cables, each with four peripheral power connectors, 17.7” (45 cm) to the first connector, 3.9” (10 cm) between connectors, modular cabling system
• Two adapters to convert peripheral power connectors into floppy disk drive power connectors

All cables use 18 AWG wires, which is the minimum recommended gauge.
The number of connectors is, in theory, adequate for a 650 W power supply, however, competing products come with four video card power connectors instead of only two, allowing you to install up to two high-end video cards that require two auxiliary power connectors each.

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Figure 4: Cables

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

A Look Inside the Corsair HX650 Gold

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, and then in the following pages we will discuss in detail the quality and ratings of the components used.

 

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Figure 5: Top view

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Figure 6: Front quarter view

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Figure 7: Rear quarter view

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Figure 8: The printed circuit board

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 the transient filtering stage, this power supply is flawless.

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Figure 9: Transient filtering stage (part 1)

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Figure 10: Transient filtering stage (part 2)

On the next page, we will have a more detailed discussion about the components used in the Corsair HX650 Gold.

Primary Analysis

On this page, we will take an in-depth look at the primary stage of the Corsair HX650 Gold. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
        

This power supply uses one GBU10JL rectifying bridge, which is attached to an individual heatsink. This bridge supports up to 10 A at 100° C. In theory, you would be able to pull up to 1,150 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 920 W without burning itself out (or 1,035 W at 90% efficiency). Of course, we are only talking about this particular component. The real limit will depend on all the components combined in this power supply.

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Figure 11: Rectifying bridge

The active PFC circuit uses two SPP20N60C3 MOSFETs, each one supporting up to 20.7 A at 25° C or 13.1 A at 100° C in continuous mode (note the difference temperature makes), or 62.1 A at 25° C in pulse mode. These transistors present a 190 mΩ maximum resistance when turned on, a characteristic called RDS(on). The lower the number the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.

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Figure 12: Active PFC transistors and diode

The active PFC circuit is controlled by an ICE3PCS01 integrated circuit.

The output of the active PFC circuit is filtered by a 470 μF x 420 V Japanese electrolytic capacitor, from Hitachi, labeled at 105° C.

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Figure 13: Capacitor

In the switching section, two P18N50C MOSFETs are employed using a resonant configuration. Each transistor supports up to 18 A at 25° C or 11 A at 100° C in continuous mode or up to 72 A at 25° C in pulse mode, with a maximum RDS(on) of 270 mΩ.
 

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Figure 14: The switching transistors

The switching transistors are controlled by an ICE2HS01G resonant controller.

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Figure 15: Resonant controller and active PFC controller

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

Secondary Analysis

As one would expect in a high-efficiency power supply, the Corsair HX650 Gold uses a synchronous design, where the Schottky rectifiers are replaced with MOSFETs. Also, the reviewed product uses a DC-DC design in its secondary. This means that the power supply is basically a +12 V unit, with the +5 V and +3.3 V outputs produced by two smaller power supplies connected to the main +12 V rail. Both designs are used to increase efficiency.

The +12 V output uses four PSMN2R6-40Y MOSFETs, each one supporting up to 100 A at 100° C in continuous mode, or up to 651 A at 25° C in pulse mode, with a maximum RDS(on) of 5.3 mΩ. These transistors are located on the solder side of the printed circuit board, using the power supply case as their heatsink.

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Figure 16: The +12 V transistors

As explained, the +5 V and +3.3 V outputs are produced by two DC-DC converters, located on a daughterboard soldered to the main printed circuit board. The converters are controlled by a single APW7159 integrated circuit and use seven IPD060N03L G MOSFETs. Four of them are used by the +5 V output, and three of them are used by the +3.3 V output. Each transistor supports up to 50 A at 100° C in continuous mode and up to 350 A at 25° C in pulse mode, with a maximum RDS(on) of 6 mΩ.

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Figure 17: The DC-DC converters

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Figure 18: The DC-DC converters

The outputs of the power supply are monitored by a PS223 integrated circuit, which supports over voltage (OVP), under voltage (UVP), and over current (OCP) protections. There are four OCP channels, one for +3.3 V, one for +5 V, and two for +12 V. The manufacturer, however, decided to use only one of the +12 V channels available, resulting in this unit having a single +12 V rail.

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Figure 19: Monitoring circuit

This power supply uses a mix of solid and electrolytic capacitors in its secondary. The electrolytic capacitors are also Japanese, from Chemi-Con and Rubycon, and labeled at 105° C, as usual.

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Figure 20: Capacitors

The +5VSB Power Supply

The +5VSB (a.k.a. standby) power supply is independent of the main power supply, since it is on continuously.

The +5VSB power supply uses an ICE2QR47565 integrated circuit, which incorporates the PWM controller and the switching transistor into a single chip.

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Figure 21: The +5VSB integrated circuit with an integrated switching transistor

The rectification of the +5VSB output is performed by an SBR10U45D1 Schottky rectifier present on the solder side of the printed circuit board. This component supports up to 10 A (5 A per internal diode at 110° C, 0.57 V maximum voltage drop).

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Figure 22: The +5VSB rectifier

Power Distribution

In Figure 23, you can see the power supply label containing all the power specs.

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Figure 23: Power supply label

As you can see, this unit has a single +12 V rail configuration.

Let’s find out how much power this unit can deliver.

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 and +12VB inputs were connected to the power supply’s single +12 V rail. (The +12VB input was connected to the power supply EPS12V connector.)

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	5 A (60 W)	10 A (120 W)	14.5 A (174 W)	19 A (228 W)	23.5 A (282 W)
+12VB	5 A (60 W)	10 A (120 W)	14 A (168 W)	19 A (228 W)	23.5 A (282 W)
+5 V	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)	1.5 A (7.5 W)	2 A (10 W)	2.5 A (12.5 W)	3 A (15 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	138.6 W	270.6 W	392.5 W	525.4 W	651.4 W
% Max Load	21.3%	41.6%	60.4%	80.8%	100.2%
Room Temp.	47.3° C	46.5° C	46.9° C	48.2° C	46.9° C
PSU Temp.	48.4° C	48.5° C	48.5° C	49.0° C	50.5° C
Voltage Regulation	Pass	Pass	Pass	Pass	Pass
Ripple and Noise	Pass	Pass	Pass	Pass	Pass
AC Power	159.5 W	302.6 W	438.9 W	594.5 W	750.0 W
Efficiency	86.9%	89.4%	89.4%	88.4%	86.9%
AC Voltage	117.1 V	115.9 V	114.7 V	113.1 V	111.0 V
Power Factor	0.992	0.996	0.998	0.998	0.998
Final Result	Pass	Pass	Pass	Pass	Pass

The 80 Plus Gold certification promises efficiency of at least 87% under light (i.e., 20%) load, 90% under typical (i.e., 50%) load, and 87% under full (i.e., 100%) load. The Corsair HX650 Gold was able to match these numbers for light and full loads at high temperatures. We didn’t test this unit at 50% load, but from the numbers achieved at 40% and 60% load, we can easily assume it can provide 90% efficiency at half of its labeled wattage.

Let’s discuss voltage regulation on the next page.

Voltage Regulation Tests

The ATX12V specification states that positive voltages must be within 5% of their nominal values, and negative voltages must be within 10% of their nominal values. We consider a power supply as “flawless” if it shows voltages within 3% of its nominal values. In the table below, you can see the power supply voltages during our tests and, in the following table, the deviation, in percentage, of their nominal values.

The Corsair HX650 Gold presented outstanding voltage regulation, with all positive outputs within 2% of their nominal values, as you can see below.

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	+12.20 V	+12.16 V	+12.14 V	+12.10 V	+12.08 V
+12VB	+12.20 V	+12.16 V	+12.12 V	+12.08 V	+12.03 V
+5 V	+5.08 V	+5.06 V	+5.05 V	+5.03 V	+5.01 V
+3.3 V	+3.34 V	+3.33 V	+3.30 V	+3.29 V	+3.27 V
+5VSB	+5.01 V	+4.98 V	+4.96 V	+4.93 V	+4.90 V
-12 V	-11.30 V	-11.49 V	-11.70 V	-11.97 V	-12.25 V

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	1.67%	1.33%	1.17%	0.83%	0.67%
+12VB	1.67%	1.33%	1.00%	0.67%	0.25%
+5 V	1.60%	1.20%	1.00%	0.60%	0.20%
+3.3 V	1.21%	0.91%	0.00%	-0.30%	-0.91%
+5VSB	0.20%	-0.40%	-0.80%	-1.40%	-2.00%
-12 V	6.19%	4.44%	2.56%	0.25%	-2.04%

Let’s discuss the ripple and noise levels on the next page.

Ripple and Noise Tests

Voltages at the power supply outputs must be as “clean” as possible, with no noise or oscillation (also known as “ripple”). The maximum ripple and noise levels allowed  are 120 mV for +12 V and -12 V outputs, and 50 mV for +5 V, +3.3 V and +5VSB outputs. All values are peak-to-peak figures. We consider a power supply as being top-notch if it can produce half or less of the maximum allowed ripple and noise levels.

The Corsair HX650 Gold provided extremely low ripple and noise levels, as you can see below.

Input	Test 1	Test 2	Test 3	Test 4	Test 5
+12VA	10.0 mV	13.6 mV	17.2 mV	24.2 mV	29.4 mV
+12VB	9.4 mV	12.8 mV	14.8 mV	20.8 mV	25.0 mV
+5 V	5.4 mV	6.8 mV	7.8 mV	10.4 mV	13.0 mV
+3.3 V	6.8 mV	7.2 mV	8.6 mV	9.2 mV	13.6 mV
+5VSB	8.2 mV	11.2 mV	14.2 mV	16.4 mV	19.8 mV
-12 V	9.6 mV	10.6 mV	16.2 mV	28.4 mV	31.8 mV

Below you can see the waveforms of the outputs during test five.

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Figure 24: +12VA input from load tester during test five at 651.4 W (29.4 mV)

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Figure 25: +12VB input from load tester during test five at 651.4 W (25.0 mV)

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Figure 26: +5V rail during test five at 651.4 W (13.0 mV)

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Figure 27: +3.3 V rail during test five at 651.4 W (13.6 mV)

Let’s see if we can pull more than 650 W from this unit.

Overload Tests

Below you can see the maximum we could pull from this power supply. The objective of this test is to see if the power supply has its protection circuits working properly. This unit passed this test, since it shut down when we tried to pull more than what is listed below. During this test, noise and ripple levels were still extremely low and voltages were within 3% of their nominal values.

Input	Overload Test
+12VA	29 A (348 W)
+12VB	29 A (348 W)
+5 V	10 A (50 W)
+3.3 V	10 A (33 W)
+5VSB	3 A (15 W)
-12 V	0.5 A (6 W)
Total	794.8 W
% Max Load	122.3%
Room Temp.	44.8° C
PSU Temp.	48.6° C
AC Power	938.0 W
Efficiency	84.7%
AC Voltage	110.1 V
Power Factor	0.998

Main Specifications

The main specifications for the Corsair HX650 Gold power supply include:

• Standards: ATX12V 2.31 and EPS12V 2.92
• Nominal labeled power: 650 W at 50° C
• Measured maximum power: 794.8 W at 44.8° C
• Labeled efficiency: 80 Plus Gold certification (87% at light/20% load, 90% at typical/50% load, and 87% at full/100% load)
• Measured efficiency: Between 86.9% and 89.4% at 115 V (nominal, see complete results for actual voltage)
• Active PFC: Yes
• Modular Cabling System: Yes, partial
• Motherboard Power Connectors: One 20/24-pin connector and two ATX12V connectors that together form an EPS12V connector, permanently attached to the power supply
• Video Card Power Connectors: Two six/eight-pin connectors on two cables, modular cabling system
• SATA Power Connectors: Eight on two cables, modular cabling system
• Peripheral Power Connectors: Eight on two cables, modular cabling system
• Floppy Disk Drive Power Connectors: Two through adapters
• Protections (as listed by the manufacturer): Over voltage (OVP), under voltage (UVP), over current (OCP), and short-circuit (SCP) protections
• Are the above protections really available? Yes.
• Warranty: Seven years
• Real Model: Seasonic G-650
• More Information: http://www.corsair.com
• Average Price in the U.S.*: USD 120.00

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

Conclusions

The Corsair HX650 Gold is a great power supply, with efficiency above 87% at high temperatures, excellent voltage regulation for its positive voltages, and extremely low noise and ripple levels. It also comes with a terrific price tag for what it offers (USD 120). The only negative point we could find with this power supply is the presence of only two video card power connectors, while competing products come with four.

It is USD 5 cheaper than the model it is derived from, the Seasonic G-650, but if you can spend USD 10 more, the Seasonic X-Series KM3 650 W is a better option, as it has a fully modular cabling system, four video card power connectors, higher efficiency, and even better voltage regulation.