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Corsair AX1200i Digital ATX Power Supply Preview
Date: Aug 06, 2012
Author: Marco Chiappetta
Introduction, Specs and Bundle

Corsair is one of the few companies in the PC enthusiast space that has been able to expand their product offerings, while also maintaining or even bolstering their solid reputation in the community. All too often, a company will attempt to build upon some initial success by entering a new market with a “me too” or re-badged product and end up losing credibility with enthusiasts along the way. Corsair seems to take a different approach, however. Instead of simply re-branding a product just to quickly gain a presence in a new or fledgling market, Corsair, more often than not, seems to bide their time to customize or design a product (or product family) to specifically cater to enthusiasts. And then they launch it with a clearly defined feature set that differentiates the Corsair products from the competition. Of course it also helps that Corsair seems to design some of the more aesthetically appealing and best performing products for enthusiasts as well.

Corsair’s attention to detail and understanding of the enthusiast community has allowed the company to evolve from a memory manufacturer into a well-regarded supplier of cases, cooling hardware, input devices, PC audio, power suppliesgaming accessories and storage devices. Their latest product, the Corsair AX1200i Digital ATX Power Supply, takes things a step further and blazes a trail by adding some innovative and useful features not found in any competing products.

The Corsair AX1200i Digital ATX Power Supply’s name hints at this PSU’s 1200 watt rating, but beyond its monstrous power output, the AX1200i is also highly efficient and sports a Digital Signal Processor (DSP) to provide digitally-controlled power and an interface to Corsair’s Corsair Link software for real-time monitoring and control. There are quite a few other features to the AX1200i worth mentioning as well, which we’ll get to on the pages ahead. First up, here’s a quick peek at some of the unit’s specs and a look at what Corsair includes in the AX1200i’s box...

The Corsair AX1200i Digital ATX PSU

Corsair AX1200i Digital ATX Power Supply
Specifications & Features
Warranty 7 years
Dimensions 50mm x 86mm x 200mm
Modular Fully Modular
Power Output 1200 watts
80 Plus Certifications Platinum
ATX Connector 1
EPS Connector 2
PCI-E Connector 6
4-Pin Peripheral Connector 12
SATA Connector 16
Floppy Connector 2 (via adapters)
MTBF 2,000,000 hours

Corsair AX1200i PSU Cable Bundle

Corsair includes a myriad of cables with the AX1200i PSU, in addition to a few other accessories. The cable break-down is detailed in the list of specifications above. As you can see in the list, there are a multitude of SATA (16), 4-pin peripheral (12), and PCI Express (6) power connectors / cables present, along with a couple of adapters that’ll convert two of the 4-pin connectors to floppy connectors. Also included with the AX1200i is a bag with mounting screws, 10 nylon zip-ties, a “Powered by Corsair” case badge, and a strip of double-sided tape to facilitate mounting of the Corsair Link device.

Corsair Link USB Dongle

The Corsair AX1200i is able to interface with Corsair’s Link software through the included Corsair Link USB dongle. The dongle connects to an available motherboard USB header and then a thin cable connects the Link device to the PSU. We’ll talk a little more about the Corsair Link device and dongle a little later.

Corsair AX1200i: A Closer Look

The Corsair AX1200i Digital PSU features a fully modular design, which means all of its cables, including the ATX and EPS cables, can be removed. Some would argue that having a connector in-line with these critical power leads adds resistance and potentially dirties the feed, which is technically correct, but in practice the effects are minimal. Regardless, that’s the reason it’s common to find partially modular power supplies on the market as well.

Corsair AX1200i Digital PSU: Fully Modular Connectors, 140mm Cooling Fan

In terms of its physical dimensions, the Corsair AX1200i isn’t any larger than other high-end power supplies in its class. The unit measures 50mm x 86mm x 200mm, not including any depth added by attached cables. Both sides of the unit are adorned with attractive “Corsair AX1200i” badges, while the top sports a single decal with technical specifications. The bottom of the unit is home to a single, 140mm cooling fan. The inside face of the AX1200 is loaded with modular connectors and a self-test button, while the outside face has a power switch and a 3-pin power cord receptacle.

The AX1200i’s technical specifications are impressive to say the least. The unit features a single +12v rail design with a max output rating of 100.4A, or 1204.8W. The +3.3v and +5v feeds are rated for 30A each. Corsair claims the units are tested at 50’C ambient temperature to derive these ratings, which is a higher temperature than where most power supplies are tested. Although the unit has a single +12v rail design, we should point out that the AX1200i’s DSP and digitally-controlled power output can be configured as a virtual multi-rail device as well, with individual PCI-E over-current protection (OCP) trip points. The AX1200i also features digital interleaved power factor (PF) and PWM control, Over-Voltage Protection (OVP) and Over-Current Protection (OCP) on the 12v, 5v, and 3.3v rails, Over-Temperature Protection (OTP), and Short-Circuit Protection (SCP).

The AX1200i's DSP Control Board Is visible in the foreground...

Although its relatively high output power rating is attractive, the real standout feature of the Corsair AX1200i is its digitally controlled power. The AX1200i is the first desktop PC power supply to use a DSP, or Digital Signal Processor, to provide ultra-tight voltage regulation, < +/- 1.5% on the +12v rail according to Corsair, with low ripple and noise that’s up to 3x better than the ATX specification. The DSP also allows for dynamic, on-the-fly performance tuning and optimization.

In addition to DSP control, the AX1200i features individual DC-DC regulation for its 3.3v, 5v and 12v rails, and secondary side synchronous rectification, which utilizes lower-loss MOSFETs than more conventional output rectification schemes. The modular connector board’s PCB is also comprised of 4-layers to ensure a better ground return plane, lower resistance and low voltage drops than less sophisticated modular PSUs.

The Corsair AX1200i features a server-grade power train architecture and uses high-temp, Japanese capacitors

The use of a DSP in the control circuit also allowed Corsair to decrease the number of discrete components within the PSU. And because the AX1200i uses Zero Voltage Switching and Zero Current Switching (ZVS / ZVC) technology as well, the end result is very high efficiency. In fact, the unit is rated for 92%+ efficiency and has earned an 80 PLUS Platinum rating. The integration of a DSP (and inclusion of a Corsair Link USB dongle) also gives the AX1200i the ability to interface with Corsair’s Corsair Link real-time monitoring and control software, which we’ll talk about on the next page.

Other features of the Corsair AX1200i Digital PSU include a low-noise 140mm PWM cooling fan and a handy self-test switch. The cooling fan ramps up based on load, but won’t even spin until the load on the PSU exceeds 30% or 360W. The high efficiency of the PSU also results in less heat output than typical power supplies though, which minimizes the need for loud, active cooling. Throughout our real-world testing, the fan in the AX1200i was barely audible. Even when we manually cranked the fan speed up to 100%, it was still very quiet and barely audible over our other system components.

The self-test switch is also something new to the desktop PSU world, at least in our experience. With a push of a button, the AX1200i will run a series of diagnostic tests to ensure the cooling fan and DC output voltage rails are working properly. We hope you’ll never have to use it, but the inclusion of a self-test switch is a quick, simple way to test the PSU and could save users considerable time when diagnosing system failures.

Corsair Link Software

Due to the AX1200i’s DSP-related features and capabilities, the Corsair AX1200i requires a few extra installation steps, over and above any standard PSU. In addition to (obviously) mounting the unit and connecting any cables that are necessary for your system, AX1200i users need to connect the Corsair Link USB dongle and install the Corsair Link Dashboard software.

The Corsair Link USB dongle is the physical interface between the AX1200i and a system. One end of the Corsair Link dongle connects to an available USB header on a motherboard; the other end has a 4-pin receptacle for a thin cable, which connects to the dongle and to a special connector on the PSU itself. Although the unit comes with a Corsair Link dongle, we should also point out that the AX1200i is compatible with the multi-port Corsair Link Commander as well.

Corsair Link Dashboard v2 Main Screen (Note: The case image and widget locations are customizable)

Once the unit is physically connected to a system, the necessary drivers and the Corsair Link Dashboard software must also be installed, or more specifically the latest Corsair Link Dashboard v2 software must be installed (the drivers are included in the installer).

The Corsair Link Dashboard will display different information, depending on the components used in the system. Typically though, you can expect to find CPU and GPU temperatures, HDD and SSD temperatures, various fan speeds, and of course information regarding the AX1200i. By default, the main screen will show a picture of a case (which can be customized) with system health data in the left pane. The temperature and fan speed widgets in the left pane, however, can be dragged over their actual location in the virtual case, as seen in the image above.

Corsair Link Dashboard v2 Power Tab

There are tabs along the top of the Corsair Link Dashboard interface as well, that will reveal various menus within the app. The Groups tab will show temperature, fan speed and load data for defined groups of components, while the Graph tab shows similar data graphed out over time. The Options tab reveals various user-configurable settings within the utility, like its skin and notifications. It’s the Power tab where most of the AX1200i’s main features are exposed, however.

Under the power tab, users can define the over-current trip points for the PCI-E connectors to enable virtual multi-rail mode and all voltage and efficiency data is displayed. Corsair Link will show power-in, power-out, and the actual voltage level on all rails and connectors in real-time. It also uses the power-in/out data to calculate efficiency in real-time.

Performance Summary and Conclusion

Performance Summary: In lieu of a thermally controlled PSU testing environment and specialized tools to monitor actual power output, we tested the Corsair AX1200i Digital PSU the way the vast majority of you reading this would—we connected it to a few systems and beat on the unit to see if it would fail.For the last couple of weeks, we’ve had the Corsair AX1200i connected to an overclocked Core i7-3770K-based system running at 4.4GHz, outfitted with 16GB of RAM, a 10K RPM HDD, and an overclocked GeForce GTX 680. The unit was also connected to a dual-CPU powered beast outfitted with two Intel Xeon 5680 processors (12 physical cores total) running at 3.9GHz, 24GB of RAM, dual SSDs in a RAID configuration, a 2TB HD, and a pair of Radeon HD 6970 graphics cards running in CrossFire mode.

The overclocked Core i7-based system would readily consume over 400W when running games, while the dual-CPU monster had no trouble breaking the 800W mark for extended periods under load. Throughout all of our testing, the Corsair AX1200i worked flawlessly. We never experienced any instability and the PSU’s cooling fan always remained quiet. Even though the AX1200i’s fan did have to spin up considerably when in the dual-Xeon powered rig, there was no way it could be heard over the pair of graphics cards.

While these tests don’t quantify ripple, noise, or output quality, they do show that the Corsair AX1200i is perfectly capable of powering some immensely powerful systems, without issue.

The fully-modular, Corsair AX1200i Digital ATX Power Supply

The Corsair AX1200i Digital PSU should be available right away at your favorite e-tailers for a price around $349. With that kind of asking price, the AX1200i is certainly one of the more expensive power supplies on the market, although not the most expensive in its class. While we would love to see the features of the AX1200i trickle down to more affordable, lower-power models, at its current price, the AX1200i is still compelling in light of competing offerings. We dig the fully-modular cables on this unit, appreciate the low-noise fan, and think the features and capabilities afforded by the DSP and Corsair Link software set the AX1200i apart in the enthusiast PSU space. We also like the fact that the unit never faulted, even when being taxed by a 2P, dual-GPU powered beast of a system.

Users in the market for a high-end power supply will be well served by the Corsair AX1200i. Even if you don’t plan to use the Corsair Link Dashboard software and tinker with the unit, the AX1200i is still a killer power supply. Factor in its high-output, stability, efficiency, quiet operation, and innovative features though, and you’ve got an enthusiast-class power supply that’s worthy of consideration for any high-end PC build.

  • DSP Control
  • Quiet Operation
  • Fully Modular
  • Highly Efficient
  • Relatively Expensive
  • Corsair Link Dashboard Software Could Use Some Refinement

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