Corsair AX860 Modular PSU- Introduction

Ever since last summer, Corsair's digital power supplies have been in the scopes of almost every technology junkie. Looking back to our reviews of the AX1200i and the AX760i, we can easily see why. However, not every enthusiast needs or even wants the digital interface, which led Corsair to release the AX760 and AX860, "classic" versions of the digital AX760i and AX860i respectively. The differences however are many more than just the digital interface; read on to find out.

The Corsair AX860 PSU

It is the AX860 which found its way on our test bench today, the strongest AX non-digital model which Corsair currently produces. It can be found retailing for $199 + shipping, a good $30 less than the digital AX860i. As the rest of their features are almost the same, both have the same number of connectors and both come with an 80Plus Platinum certification, most people would make an educated guess and think that the AX860 is the same as the AX860i, minus the digital interface; however, such an assumption would be wrong. There even are distinct visual dissimilarities between the two models and they are entirely different on the inside. How can the "classic" AX860 stand in comparison to the digital models of the series then? We will find out in this review.

Fan Engine Logo Close Up

Manufacturer’s features

Manufacturer’s specifications



Seven years


150mm x 86mm x 160mm




860 Watts

80 Plus


ATX Connector


EPS Connector


PCI-E Connector


4 Pin Peripheral Connector


SATA Connector


Floppy Connector



100,000 hours

Unboxing the Corsair AX860

The box

Corsair supplies the AX860 in a dark cardboard box with glossy red decoration, instilling a serious, professional theme. The box is very sturdy and the walls are thick, with the AX860 well secured between polyethylene foam slabs on the inside as well as wrapped inside a reusable cloth pouch, ensuring its safe transportation.

The box (rear)

The company virtually turned the back side of the box into a short manual, fitting a table with the electrical specifications of the AX860, two graphs displaying the efficiency and the acoustics of the power supply, a list with the number of connectors and a description of its major features.


Inside the box we found a black and white manual, the necessary A/C power cable, a set of mounting screws, a few small cable ties and a case sticker. There is also a nylon bag which holds all of the unit's cables, since it’s a fully modular design. The Molex, Floppy and SATA cables are all-black, flat cables. Corsair used black sleeving on the rest of the cables but also used only black cables rather than color-coded, which definitely looks much better. Unfortunately there are no cable straps, which is a common sight in high end power supply bundles. 

External Design of the AX860

The Corsair AX860 PSU

Although the AX860 is physically similar to the AX760i/AX860i models, it is not quite the same. The ribbed design at the bottom of the power supply is gone and the unique fan guard has been replaced with a standard circular one. Still, the chassis remains only 160mm (6.3") long, allowing it to fit inside virtually any ATX-compliant case, and Corsair sprayed with the same quality matte black paint as with every other AX series power supply.

Side stickers

The side stickers of the AX860 are matte, with the company logo to the left and the model's logo dominating the rest of the sticker. The sticker is placed in an embossed area between two decorative lines.

Top side sticker

The sticker with the detailed electrical specifications of the AX860 has been placed on the top side of the chassis, where it will be visible through a windowed side panel only if the case has the PSU mounting area towards its bottom and the unit's fan is still facing downwards.

Rear Side

Much like any other AX series power supply, the rear side of the fully modular AX860 is littered with connectors for the modular cables. There are two connectors for the single 24-pin ATX cable, six connectors for PCIe devices and CPU EPS cables and five connectors for the SATA/Molex device cables. If all cables are installed in the aforementioned connectors, the AX860 provides a total of two EPS 12V connectors, six 6+2 pin PCIe connectors, eight Molex connectors and twelve SATA connectors; a very healthy number of connectors considering the output of this power supply. There are also two floppy disk adapters but which negate one Molex connector each if used. Finally, a small switch can be seen at the top right corner, which can be used to set the fan control to either "normal" or "hybrid". When in hybrid mode, the fan is generally quieter and will even stop when the unit's load is very low, while the normal mode is more aggressive towards cooling.

Front Side

The front side of the AX860 is the standard perforated honeycomb mesh design, with only the standard on/off switch and power plug receptacle are to be found, as well as a small sticker with the unit's model.

A look inside the AX860

The cooling fan

Unlike the vast majority of Corsair's units which are being cooled by Yate Loon fans, the cooling fan of the AX860 is provided by Sanyo Denki. It is a fairly fast 120mm fan, capable of reaching a maximum speed of 2200RPM. With dual ball bearings, it may be not the quietest fan around but it certainly is one of the most reliable.

Inside the Corsair AX860 unit

Here is where the major difference of the AX860 in comparison to the AX760i/AX860i models lies; this is no Flextronics design at all, as Corsair chose their old friends at Seasonic to be the manufacturers of this power supply. This makes the AX860 virtually nothing more than an upgrade of the older AX850, as Corsair switched from the second generation to the third generation KM platform. Seasonic is relentless when it comes to the quality of their high-end designs and the AX860 is no exception; both the soldering job and the assembly quality are nothing short of textbook.

The filtering stage

Seasonic placed a small PCB at the rear of the A/C receptacle which holds some of the input filter components and shielded it within a metallic cage to prevent EMI interference. The total filtering stage components are six Y capacitors, three X capacitors, three chokes and a MOV, many more than the minimum required to build an effective transient filter.

Primary side

Moving towards the APFC, we found the two bridge rectifiers mounted on their own small dedicated heatsink, right before the sizable coil. Two Nippon Chemi-Con 400V/390uF 105°C capacitors complete the primary filtering stage passive components. The active components, two transistors and a diode, are on the large heatsink at the edge of the main PCB. The smaller heatsink towards the main transformer holds the four inversion transistors, which form a full bridge topology.

Secondary side

An LLC type rectifier is being formed on the secondary side of the AX860, housed on the short vertical PCB next to the main transformer. The peculiar looking heatsink is used to cool the rectifier's transistors. Around the secondary side we found Nippon Chemi-Con electrolytic and Enesol solid state capacitors.

Modular connector PCB

Seasonic moved the DC to DC converters which generate the 5V and 3.3V lines directly on the PCB which is holding the modular cable connectors. Additional filtering takes place on this PCB as well.

Test Setup

The load

In order to be able to effectively and efficiently test any computer power supply unit, we developed and constructed our own proprietary testing station. Our testing station consists of a number of power resistors and small capacitors, which in turn are connected to a RS485 electronic relay array which allow our load to be controlled through computer software alone.

USB interface and connection panel

When accuracy and speed are of critical importance, a simple multimeter or voltage meter is not sufficient for the task. To ensure the quality of our testing, an USB laboratory interface is being used to continuously monitor and record the readings of all voltage lines simultaneously. For ripple measurements, an oscilloscope is necessary and we chose the USB Instruments Stingray, the most widely used oscilloscope amongst low voltage PSU engineers and testers.

Measurement instruments

For accurate testing and repeatable results, a stable power input is also required. Thus, we are providing power to our test samples through a 3kVA VARIAC which allows us to control the input voltage of our test samples and also perform efficiency tests under both 110V AC and 230V AC input. A Lutron DW-6091 is also being used, monitoring the input voltage, real and apparent power, power factor and amperage.

The software

A power supply testing procedure would not be complete without thermal and acoustics tests. For our acoustics tests we are using a SL-5868P digital sound level meter, placed 1 meter away from the unit (DIN standard). Two PT100 sensors and their respective displays are being used to monitor the ambient temperature and the exhaust temperature of the unit.

Complete test setup during trial run


Testing results (Regulation & Ripple)





Despite the lower price and different OEM, the electrical performance of the AX860 remains astounding. This is the first power supply we have ever tested capable of regulating all of its voltage lines within 0.6% across the entire load range, shattering the vast percentage of its opposition on that particular front. The voltage ripple filtering is also exceptional, with the maximum ripple we recorded being 24mV on the 12V line at maximum load, a mere sixth of the 120mV design limit.

Testing results (Efficiency, Noise & Thermal)


True to its 80Plus Platinum certification, the AX860 delivers efficiency levels of over 91% across its entire range and regardless of the input voltage. When powered from a 230V source, the efficiency peaks at 94.2%. This figure drops down to 93.3% if the voltage source magnitude is reduced to 110V, which is still much higher than what the 80Plus Platinum certification requires.


We recorded no noise level readings up to 40% load because the fan was entirely stopped up to that point. At 40% load, where the fan started, the AX860 was entirely quiet. That however quickly changed as the fan speed increased considerably after increasing the load by less than 100W, making the AX860 clearly audible from 3ft distance. Nevertheless, the speed of the fan did not increase much further after that point, not even at maximum load, allowing the noise levels of the AX860 to remain within comfortable working limits.


The temperature chart of the AX860 is erratic because of the fan's cooling profile, which does not even start at low loads. The high efficiency of the AX860 allows it to keep its working temperatures low, even at maximum load, where the temperature delta reached only up to 8°C. 

Corsair AX860 Review Conclusion

Before we began testing the AX860, we honestly were preconceived that it could be a great product but no match for its digital counterpart, the performance of which had already astonished us last month; However, the AX860 managed to positively surprise us as its performance not only was comparable to that of the digital model but there were tests that it even managed to overtake the Flextronics design.

Regarding the overall performance of the AX860, we can say little, as the results of the previous two pages speak for themselves. The electrical performance of the AX860 is setting new milestones, with efficiency which easily grant it the 80Plus Platinum certification, unequaled voltage regulation and excellent ripple suppression. This high efficiency allowed Corsair to implement the Hybrid fan mode, allowing the fan to completely stop while the internal temperature of the AX860 is low, allowing the power supply to operate noiselessly while the system is idling or performing trifling operations, such as when watching/listening to media or web browsing. Considering the capacity of the AX860, it is highly likely that the fan will never even start if the system is using a typical new CPU and an average VGA card.

The Corsair AX860

Quality-wise, the Corsair AX860 is an impressive specimen. Commenting on how much effort Seasonic is placing on sustaining very high quality standards on their high end designs feels redundant; they are not one of the favorite companies amongst hardcore overclockers and enthusiasts for no reason. The AX860 is made by using the finest quality components and the grade of the assembly job is nothing short of textbook. It is no wonder that Corsair supports these units with a 7 year long warranty, a time frame in which the vast majority of enthusiasts and gamers will have their systems upgraded at least twice.

The AX860 is not all about performance; even though the design of this power supply is a little simpler than that of its digital AX860i counterpart, the AX860 remains a visually interesting product. It might be a subtle all-black design but Corsair ironed out the blunders which many other companies fall prey to, such as the use of black wires and connectors for every cable, creating a product that will easily match the interior of most modern high performance systems.

Inside the AX860 - Seasonic M3

We found the AX860 retailing for $199 + shipping, $30 less than the digital AX860i; a worthwhile monetary difference for those who were not impressed by the digital Corsair Link interface of the –i variants of the series. The AX860 obviously is by no means a cheap power supply, making it nearly twice as expensive as a "mainstream" 850W unit, but it is clearly not a product meant for the mainstream market. Considering the 80Plus Platinum certification and the power rating of the AX860 alone, the retail price actually is very competitive; take the long warranty and awesome performance into consideration and then the list of the units capable of competing with the AX860 becomes very, very short. And if you power requirements are not as high, you can go for the AX760 model for $20 less.

Legit Bottom Line: Are you seeking a very high performance and quality product within the 800W-900W power range and the digital Link interface of the AX-i models finds you indifferent? Congratulations, you probably found the best such product which you can invest on at this point of time.