Corsair AX760i Power Supply Review
By Gabriel Torres on November 6, 2012


Introduction

Hardware Secrets Golden Award

Today, Corsair is releasing two new models within its AX “i” power supply series, the AX760i and the AX860i. These power supplies and the AX1200i have an internal digital signal processor, which allows never before seen voltage regulation and noise and ripple levels. In addition, you can monitor all of the parameters of the power supply on your computer through a USB-based connection called Corsair Link. Let’s take an in-depth look at the AX760i, which also comes with a fully modular cabling system and the 80 Plus Platinum certification.

The AX “i” power supplies are targeted to the ultimate enthusiast, who understands the advantages of having a technically flawless power supply. Two of the highlights of the reviewed power supply are its voltage regulation and noise and ripple levels.

Voltages have to be as close to their nominal values as possible. The ATX12V specification allows outputs to be within 5% of their nominal values (10% for the -12 V output). We consider a power supply to be “flawless” when its outputs are within 3% of their nominal values. With the AX760i, Corsair promises 1.5% voltage regulation for the +12 V, +5 V, and +3.3 V outputs, and 3% voltage regulation for the +5VSB and -12 V outputs. This is simply unheard of.

As for ripple and noise levels, the ATX12V specification allows them to be up to 120 mV at the +12 V and -12 V outputs and up to 50 mV on the +5 V and +3.3 V outputs. Corsair promises maximum ripple and noise levels of 40 mV for the +12 V, -12 V, and +5VSB outputs, and 30 mV for the +5 V and +3.3 V outputs. Of course, during our tests we will check to see if these claims are true.

Another highlight of the Corsair AX760i is a “self-test” button, which commands the power supply to check if it is working properly. (This function tests the fan as well.)

Corsair AX760i PSU
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Figure 1: Corsair AX760i power supply

Corsair AX760i PSU
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Figure 2: Corsair AX760i power supply

The Corsair AX760i is 6.3” (160 mm) deep. It uses a 120 mm ball-bearing fan on its bottom (Yate Loon D12BH-12). Note, in Figure 3, how there is a thermal sensor (the green component) right in front of the fan. This fan remains off while the power supply is delivering up to 30% of its labeled wattage (i.e., up to 228 W).

Corsair AX760i PSU
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Figure 3: Fan

The modular cabling system from this power supply has 15 connectors: two for the main motherboard power connector, six for video card and ATX12V/EPS12V connectors, six for peripheral and SATA connectors, and one for the Corsair Link device. This power supply comes with the following cables:

All wires are 18 AWG, which is the minimum recommended gauge, except for the main motherboard cable, which uses thicker wires (16 AWG).

The number of connectors is outstanding for a 760 W power supply, allowing you to install up to three high-end video cards that require two auxiliary power connectors each. The number of SATA power connectors (12) is also impressive.

Corsair AX760i PSU
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Figure 4: Cables

In Figure 5, you can see the Corsair Link device, which allows you to monitor the power supply using Corsair’s software.

Corsair AX760i PSU
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Figure 5: Corsair Link

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

A Look Inside the Corsair AX760i

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.

Corsair AX760i PSU
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Figure 6: Top view

Corsair AX760i PSU
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Figure 7: Front quarter view

Corsair AX760i PSU
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Figure 8: Rear quarter view

Corsair AX760i PSU
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Figure 9: 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, with one X capacitor and six Y capacitors more than the minimum required.

Corsair AX760i PSU
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Figure 10: Transient filtering stage (part 1)

Corsair AX760i PSU
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Figure 11: Transient filtering stage (part 2)

On the next page, we will have a more detailed discussion about the components used in the Corsair AX760i.

Primary Analysis

On this page, we will take an in-depth look at the primary stage of the Corsair AX760i. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.        

This power supply uses a GSIB2560L rectifying bridge, which is attached to an individual heatsink. This bridge supports up to 25 A at 98° C. In theory, you would be able to pull up to 2,875 W from a 115 V power grid. Assuming 80% efficiency, the bridge would allow this unit to deliver up to 2,300 W without burning itself out (or 2,588 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.

Corsair AX760i PSU
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Figure 12: Rectifying bridge

The active PFC circuit uses two IPP60R199CP MOSFETs, each one supporting up to 16 A at 25° C or 10 A at 100° C in continuous mode (note the difference temperature makes), or 51 A at 25° C in pulse mode. These transistors present a 199 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.

Corsair AX760i PSU
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Figure 13: The two active PFC transistors and the active PFC diode

The output of the active PFC circuit is filtered by one 560 µF x 420 V Japanese electrolytic capacitor, from Chemi-Con, labeled at 105° C.

Corsair AX760i PSU
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Figure 14: Capacitor

In the switching section, two IPP60R125C6 MOSFETs are employed using a resonant configuration. Each transistor supports up to 30 A at 25° C or 19 A at 100° C in continuous mode or up to 89 A at 25° C in pulse mode, with a maximum RDS(on) of 125 mΩ. 

Corsair AX760i PSU
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Figure 15: The two switching transistors

The active PFC circuit and the switching transistors are controlled by the digital signal processor (DSP) that is the heart of this power supply. The DSP used is a Freescale MC56F8014. Other chips worth mentioning are the C8051F310 and the C8051F380, which are beefed-up versions of the popular 8051 microcontroller. The C8051F310 has an analog-to-digital converter (ADC), and the C8051F380 has a USB interface, which is used by the Corsair Link connection.

Corsair AX760i PSU
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Figure 16: The digital signal processor board

Corsair AX760i PSU
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Figure 17: The digital signal processor board

The +5VSB power supply is located on a separate printed circuit board.

Corsair AX760i PSU
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Figure 18: The +5VSB power supply

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 AX760i 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 six BSC030N04NS G MOSFETs, each one supporting up to 100 A at 25° C or 84 A at 100° C in continuous mode, or up to 400 A at 25° C in pulse mode, with a maximum RDS(on) of 3 mΩ. These transistors are located on a daughterboard together with the main transformer. The +12 V filtering capacitors are also located on this board, and they are all solid.

Corsair AX760i PSU
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Figure 19: The +12 V transistors

Corsair AX760i PSU
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Figure 20: Solid capacitors used by the +12 V output

As explained, the +5 V and +3.3 V outputs are produced by two DC-DC converters, each one located on a separate printed circuit board. Each converter is controlled by an NCP1587A integrated circuit and uses four BSC050N03LS G MOSFETs, each one supporting up to 80 A at 25° C or 51 A at 100° C in continuous mode and up to 320 A at 25° C in pulse mode, with a maximum RDS(on) of 5 mΩ.

Corsair AX760i PSU
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Figure 21: One of the DC-DC converters

Corsair AX760i PSU
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Figure 22: One of the DC-DC converters

The outputs of the power supply are monitored by the digital signal processor.

Most capacitors available in the secondary are solid (see Figure 20). The few electrolytic capacitors available are also Japanese, from Chemi-Con and Rubycon, and labeled at 105° C, as usual. As you can see in Figure 23, several solid capacitors are also used on the printed circuit board of the modular cabling system.

Corsair AX760i PSU
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Figure 23: Capacitors

Power Distribution

In Figure 24, you can see the power supply label containing all the power specs.

Corsair AX760i PSU
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Figure 24: Power supply label

As you can see, this unit has a single +12 V rail configuration. However, a multi-rail configuration can be formed through the Corsair Link software, as we will show later.

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

5.5 A (66 W)

11 A (132 W)

16.5 A (198 W)

22.5 A (270 W)

28.5 A (342 W)

+12VB

5.5 A (66 W)

11 A (132 W)

16 A (192 W)

22.5 A (270 W)

28 A (336 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

151.0 W

293.3 W

437.3 W

604.4 W

759.4 W

% Max Load

19.9%

38.6%

57.5%

79.5%

99.9%

Room Temp.

47.4° C

44.7° C

45.8° C

49.4° C

46.6° C

PSU Temp.

44.2° C

46.9° C

47.9° C

50.4° C

50.3° C

Voltage Regulation

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

165.5 W

317.2 W

474.4 W

663.0 W

846.0 W

Efficiency

91.2%

92.5%

92.2%

91.2%

89.8%

AC Voltage

117.5 V

116.1 V

114.6 V

112.4 V

110.4 V

Power Factor

0.995

0.999

0.999

0.999

0.999

Final Result

Pass

Pass

Pass

Pass

Pass

The Corsair AX760i achieved outstanding results on our tests, with efficiency always above 90% at high temperatures when we pulled up to 80% of its labeled wattage (608 W). At 760 W, efficiency was at 89.8%, still very high and considerably above the minimum set by the 80 Plus Platinum certification for this load (87%).

Voltage regulation was also outstanding, with all voltages within the ultra-tight regulation promised by the manufacturer (1.5% for the +12 V, +5 V, and +3.3 V outputs, and 3% for the +5VSB and -12 V outputs). 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.

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 AX760i provided extremely low ripple and noise levels, as you can see in the table below. It is really rare to see a power supply offering less than 10 mV of noise and ripple levels at full load at +5 V, +3.3 V, +5VSB, and -12 V at the same time.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12VA

8.6 mV

9.0 mV

12.0 mV

15.4 mV

20.8 mV

+12VB

8.6 mV

9.4 mV

11.8 mV

15.2 mV

20.8 mV

+5 V

5.2 mV

8.0 mV

11.4 mV

8.4 mV

9.8 mV

+3.3 V

3.8 mV

4.2 mV

5.0 mV

6.2 mV

6.4 mV

+5VSB

4.6 mV

7.2 mV

10.6 mV

7.0 mV

7.8 mV

-12 V

4.6 mV

5.6 mV

6.2 mV

6.4 mV

7.2 mV

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

Corsair AX760i PSU
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Figure 25: +12VA input from load tester during test five at 759.4 W (20.8mV)

Corsair AX760i PSU
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Figure 26: +12VB input from load tester during test five at 759.4 W (20.8 mV)

Corsair AX760i PSU
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Figure 27: +5V rail during test five at 759.4 W (9.8 mV)

Corsair AX760i PSU
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Figure 28: +3.3 V rail during test five at 759.4 W (6.4 mV)

The Corsair Link

The Corsair Link program allows you to monitor the power supply voltages, efficiency, the AC voltage, the amount of power being delivered, the speed of the fan, internal temperature, and much more.

One amazing feature available is the possibility for you to enable over current protection (OCP) individually for each video card cable, and set the OCP trigger point for each rail (cable). While some power supplies have a switch for you to select between single-rail and multi-rail modes, the Corsair AX760i goes one step further, allowing you to determine exactly how you want each rail to be configured.

Corsair AX760i PSU
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Figure 29: The Corsair Link control panel

During our tests, we collected data with both our equipment and with Corsair Link to see if there were any substantial discrepancies between the two. See the table below. The results marked with “(1)” are the ones measured by our testing equipment, whereas the results marked with “(2)” are those reported by the power supply through the Corsair Link software.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

AC Power (1)

165.5 W

317.2 W

474.4 W

663.0 W

846.0 W

AC Power (2)

173.0 W

323.0 W

478.0 W

661.0 W

841.0 W

DC Power (1)

151.0 W

293.3 W

437.3 W

604.4 W

759.4 W

DC Power (2)

154.0 W

307.0 W

443.0 W

612.0 W

779.0 W

Efficiency (1)

91.2%

92.5%

92.2%

91.2%

89.8%

Efficiency (2)

89.0%

95.0%

92.7%

92.6%

92.6%

AC Voltage (1)

117.5 V

116.1 V

114.6 V

112.4 V

110.4 V

AC Voltage (2)

117.0 V

116.0 V

114.0 V

111.0 V

108.5 V

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, with all outputs still within their tighter-than-usual range.

Input

Overload Test

+12VA

31 A (372 W)

+12VB

31 A (372 W)

+5 V

16 A (80 W)

+3.3 V

16 A (52.8 W)

+5VSB

3 A (15 W)

-12 V

0.5 A (6 W)

Total

898.4 W

% Max Load

118.2%

Room Temp.

42.4° C

PSU Temp.

47.4° C

AC Power

1,014 W

Efficiency

88.6%

AC Voltage

109.6 V

Power Factor

0.999

Main Specifications

The main specifications for the Corsair AX760i power supply include:

Conclusions

The Corsair AX760i proved to be the best power supply we’ve ever reviewed. And it is hard to say that only 24 hours after saying that the Seasonic Platinum Fanless 520 W was the best – and it still is, if you can’t afford the AX760i.

The reviewed unit is clearly targeted to the über enthusiast who understands the importance of having a good power supply. The AX760i has 1.5% voltage regulation (which is unheard of), ultra-low noise and ripple levels, and efficiency that surpasses the requirements of the 80 Plus Platinum by a good margin.

Cable configuration couldn’t be better. The power supply comes with six video card power connectors, allowing you to install three high-end video cards at the same time, and 12 SATA power connectors.

The fan of this unit remains off until you start pulling more than 30% of its labeled wattage, guaranteeing a quiet computer when you are not playing games. And it has a unique “self-test” button.

The most impressive feature of this power supply is the Corsair Link, which allows you to not only monitor the power supply parameters such as fan speed, voltages, currents, wattages, temperatures, and efficiency, but to configure over current protection (OCP) for each video card cable individually. Furthermore, this configuration is not a simple on/off feature; it allows you to set the amount of current that will make the over current protection kick in. Each video card cable can be configured with its own individual trigger point.

Of course, all of these high-end features make the Corsair AX760i an expensive power supply at a suggested price of USD 230. While we usually don’t recommend power supplies that expensive, the Corsair AX760i is an exception due to its phenomenal set of innovations. The savvy user with a packed wallet who only demands the best won’t regret buying this product.

Originally at http://www.hardwaresecrets.com/article/Corsair-AX760i-Power-Supply-Review/1668


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