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PSU Review - Corsair AX1200 1200W 80Plus Gold
Corsair’s diversification towards the power supply unit market was perhaps the most successful one any technology products manufacturer has made until today. The company is now, only a few years afterwards releasing their first PSU, renowned as one of the best PSU manufacturers. Today we are reviewing the very flagship of Corsair’s power supply products, the AX1200 1200W unit.
Manufacturer’s features and specifications
Supports the latest ATX12V v2.31 and EPS 2.92 standards and is backward compatible with ATX12V 2.2 and ATX12V 2.01 systems
An ultra-quiet 140mm double ball-bearing fan delivers excellent airflow at an exceptionally low noise level by varying fan speed in response to temperature
80 Plus Gold certified to deliver at least 90% efficiency at 50% load
Active Power Factor Correction (PFC) with PF value of 0.99
Universal AC input from 90~264V
No more hassle of flipping that tiny red switch to select the voltage input!
A dedicated single +12V rail offers maximum compatibility with the latest components
Over-voltage and over-current protection, under-voltage protection, and short circuit protection provide maximum safety to your critical system components
High-quality Japanese capacitors provide uncompromised performance and reliability
Completely modular cable system allows you to use only the cables you need
Power supply upgrade and replacement is easy, as the cables only need to be disconnected at the power supply
Low-profile, flat cable design reduces air friction and helps maximize airflow through your computer’s chassis
A seven year warranty and lifetime access to Corsair’s legendary technical support and customer service
Dimensions: 150mm(W) x 86mm(H) x 200mm(L)
MTBF: 100,000 hours
Safety Approvals: UL, CUL, CE, CB, FCC Class B, TÜV, CCC, C-tick
Packaging and Bundle
Corsair supplies the AX1200 unit inside a large and very sturdy cardboard package. The package is very subtle for a product of this class, there is little artwork but you can find a wealth of information about the unit itself at the back side of box.
Inside the package, the power supply is very well secured between Styrofoam pieces and is enclosed inside a black pouch instead of a standard bubble bag, which pouch you can reuse for any purpose you see fit.
The bundle is fairly simple and straightforward, perhaps even poor for such a highly rated product. We expected to find at least a few cable straps. On the other hand, except from the black pouch which protects the PSU and the bag which contains the modular cables, you will only receive a standard A/C power cable, several small cable ties, black screws, a case badge with the company logo and a well written manual. It is however noteworthy to mention that most of the cables, the SATA and peripheral power cables that is, are not sleeved but they are ‘flat’, entirely black cables. The thicker cables are still all-black but they are also sleeved.
The unit's exterior
The AX1200 is painted with a matte black paint which is not showy but it also does not get dirty easily. Its chassis is longer than what the ATX standard dictates, being a little over than 20cm in length.
Corsair likes placing decorative stickers with the unit’s model and the company logo at their sides of their power supplies and the AX1200 is no exception; thankfully they did not choose a striking color this time, the stickers of the AX1200 are black.
The sticker with the unit's electrical specifications and approvals can be found at the top side of the unit.
The rear is entirely perforated to allow for the air pushed by the cooling fan to escape towards the outside of the case. The unit uses a standard AC power cable and there is an oversized rocker on/off switch at the rear.
At the front we can see the numerous connectors for the modular cables; as a matter of fact, connectors for the modular cables are all which can see. There are no native cables at all and only tiny labels are printed to indicate what each set of connectors is for This unit offers the following number of connectors:
The unit's interior
The AX1200 is cooled by a 140mm fan made by Yate Loon, a Taiwanese electronics manufacturer, and it is a ball bearing fan with a maximum rotational speed of 2800RPM. Corsair definitely likes these Yate Loon fans; we can find them in almost every single one of their power supplies.
Corsair managed to surprise us as the AX1200 is not made by either of the OEM’s (Channel Well and Seasonic) they have been cooperating with in the past; Flextronics is the OEM of the AX1200 power supply.
The filtering stage of the unit is incredible; it consists of an A/C receptacle with an integrated line filter and continues on the main PCB with four Y-type capacitors, two X-type capacitors, two ferrite coils and a surge suppressing MOV. Flextronics cleverly inserted a power relay which cuts off the power supply from the A/C source entirely once the PSU shuts down, minimizing the power consumption when the computer is off.
The two primary capacitors are made by Nichicon and are rated at 420V/470μF each. The secondary side capacitors are a mix of Nippon Chemi-Con electrolytic capacitors and solid capacitors. Instead of two large primary and secondary side heatsinks, each set of components is mounted on its own large heatsink. Flextronics probably designed the unit like this not because of the quasi-resonant topology but because they wanted to avoid heat exchange between different parts or groups of parts.
Finally, this unit is using two voltage regulator modules (VRMs) and two transformers to regulate the single, monstrous 12V rail. There is no 5V and/or 3.3V line; these are created by DC to DC circuits.
Testing equipment and performance
In order to provide you with the most professional and accurate reviews, we are using the following equipment to test the performance of power supplies:
Modified SECC steel case with thermal generation and control components installed
Custom USB controlled DC load, 2.2KW maximum power drain
3KVA VARIAC
Lutron DW-6091 Power Analyzer
USB Instruments Stingray Oscilloscope
SL-5868P digital sound level meter
CompuLAB interface
MyPClab thermal interface
Labjack U3-HV interface
Custom calibration box
Custom software
More information about our testing equipment and methodology can be found in this article:
Power Supply Unit Testing Methodology
The Corsair AX1200 1200W unit successfully completed all of our tests without any operational and/or performance problems. As a matter of fact, the electrical performance of the AX1200 is astounding; there is almost no voltage ripple on any of the power supply’s unit. Even while the AX1200 is fully loaded, we measured the voltage ripple on the 12V line to be no higher than 17mV, seven times lower than what the ATX design guide dictates.
The miraculous electrical performance of the AX1200 includes its electrical efficiency, which peaks at 92.5% under nominal load and never drops below 88.5% regardless of the input AC voltage and the unit’s load.
We expected the thermal performance of the AX1200 to be excellent, given that this is an 80Plus Gold certified unit and its high efficiency would not have the power supply wasting too much power and producing heat; once more the performance of the AX1200 surprised us, with the unit’s exhaust temperature at maximum load being lower than what we are used to see while testing 500W-600W units. Even with its high efficiency, the AX1200 still has to dissipate about 130W of heat at maximum load and yet the exhaust temperature of the power supply was only 18 degrees higher than the ambient temperature.
Because of the high thermal performance, most people would expect the AX1200 to be a very noisy power supply which relies on the large and powerful Yate Loon 140mm fan for cooling. That was not the case either, with the AX1200 not only displaying a very smooth and relatively linear rise of its dB(A) output but also very low noise levels considering the extreme power output.
Final words and conclusion
Quality (30% of the total score)
The quality of both the manufacturing process and the components of the AX1200 are remarkable. The work of Flextronics is not just good; they wrote the book on how precision and quality soldering should be and the company chose excellent quality components. It is no coincidence that Corsair is boasting about their product’s 7 year long warranty.
Quality Score 10/10
Performance (40% of the total score)
We would not be exaggerating if we said that the AX1200 delivered the best overall performance that we have seen until today. Certainly, we have seen other units delivering extraordinary performance in one or two areas but the AX1200 excels in all areas, from electrical performance to acoustics. How can a company improve the performance of a product which already smites most of the competition in every aspect?
Performance Score 10/10
Value (20% of the total score)
That one is a bit tricky. The Corsair AX1200 1200W unit certainly is not the cheapest power supply, currently retailing for about 280$ USD. It currently is not even the cheapest 1200W 80Plus Gold certified power supply. On the other hand it offers ultimate performance, a fully modular design and a 7 year old warranty. The later three can easily offset the extra cost when an enthusiast is browsing for the ultimate power supply.
Value Score 10/10
Aesthetics (10% of the total score)
We cannot complain about the appearance of the AX1200 unit. Most people will love the serious, all-black design and all-black cables, while the stickers at the sides of the unit add a classy look to it. The only pointless thing was the modular 24-pin connector which, no matter what kind of system you own, you definitely are going to use; at the same time however, it does no harm either.
Aesthetics Score 10/10
PSU Review - Corsair AX1200 1200W 80Plus Gold
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