Corsair AX1200i Digital ATX 1200-watt Power Supply Review

Introduction, Specifications, Availability and Pricing

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A little over a year ago, we took an in depth look at Corsair's AX1200. The unit proved to be quite the beast. It was packed with just about all the features you could think of at the time including a full set of modular connections, 80Plus Gold certification, near silent cooling and a ton of power. On top of that, it performed almost flawlessly. We even sent the unit over to our very own Chad Sebring for some testing of his own in his highly overclocked system. He was able to pull several hundred more MHz out of his processor and a tad bit more on the video cards. We simply couldn't recommend the unit enough, but there was always one question that loomed in the back of our heads: "Where will Corsair go from here? They have to beat it somehow don't they?"

Fast forward to now and Corsair has answered our questions. They have used the original AX1200 and improved upon it in just about every way by bringing us the AX1200i. Many are thinking that since the unit already performed so well that the only thing we are talking about are minor improvements all the way around with efficiency, DC output quality and voltage regulation.

Corsair promises all of those are in fact improved, but there is more than that to the AX1200i. Corsair has also managed to work in the Corsair Link hardware and software with the AX1200i to give you the ability to monitor the entire power supply and even do some custom configuration to how the unit performs. Can these improvements really make that much of a difference and will the integration with Corsair Link be that beneficial?

Let's dig into the unit and find out just what these changes mean and how well the new model performs.

Specifications, Availability and Pricing

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DC output has remained unchanged from the previous AX1200 power supply. Both of the minor rails are rated for 30A each with a combined maximum output of 180W. The single 12V rail is rated for 100.4A or a total of 1204.8W, which is the entire output of the power supply. Through the use of the Corsair Link software, you can configure the power supply to essentially treat each PCI-E connector as its own rail. The 24-pin Main and all peripheral connectors are excluded from this. Corsair also supplies the AX1200i with slightly beefed up 5VSB rail rated for 3.5A over the typical 3.0A we find on most units.

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As far as features go, you're going to be very hard pressed to find anything that has more than what the AX1200i offers. Not only does it score a check everywhere on our list above, but it also has the DSP and Corsair Link integration. Not only does it have the protections including over current protection, but once you enable the multi-rail mode within the Corsair Link software, you can actually set the specific OCP point that you want on each rail, up to 40A. These features combined make this the most advanced power supply to ever make it in the hands of consumers.

Corsair is launching the new AX1200i with an MSRP of $350. That is about $50 more than what the original AX1200 retailed for and is a fairly reasonable increase considering that you're getting increased features and efficiency. Newegg currently has the power supply in stock at MSRP and tack on a $5.99 shipping fee. The AX1200i is backed by Corsair's amazing seven year warranty.

Packaging

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Corsair gives us a few features on the front as well as a small shot of the fully modular power supply. Short of changing the color from gold to red, you wouldn't really be able to tell the two units apart at first glance. The Corsair Link and 80Plus Platinum logos are present here as well.

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Opening the flap on the front gives us some more information about the unit. On the top we find connector availability, but not cable lengths. The bottom half highlights the redesign of the unit with the use of DSP and upgraded/reduced components while giving a better look at the unit.

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Moving to the back, it looks like there is a lot going on here, but most of it is just due to the repetition in multiple languages. The efficiency and fan noise charts are new. Note that the fan doesn't start to operate till the power supply reaches 30% load. This can be overridden in the Corsair Link software. Speaking of which, there is a note on the back about it being "server-inspired diagnostic tools." This is quite true and we are seeing the technology start to trickle down to the consumer.

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While the top is blank sans the AX1200i logo, the bottom gives us a few more bullet points that tell us the unit has auto-switching circuitry for universal AC input and gives the dimensions of the power supply. Both sides are also blank sans the AX1200i logo.

Inside the Box

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The unit is packed well inside the box with an inch of foam around the entire unit. Modular cables and accessories take up the rest of the space and make for a snug fit. The anti-static bag contains the Corsair Link USB dongle.

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Pulling things out of the box reveals that things aren't as convoluted as they appear. The 8GB Corsair Flash Voyager mini contains a PSU test report from the factory. Also included are several zip ties, mounting screws and a case badge.

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Pulling the power supply out of the felt bag gives us a great look at the finish on the unit as well as the I/O specification label.

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One side displays the AX2100i logo.

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The other side is identical except the log is inverted in so that the label can be displayed properly no matter where it is mounted inside the case.

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On the back we find the standard honeycomb mesh exhaust grill with AC input and heavy duty rocker switch.

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The modular connections on the front are labeled neatly. There is no need to list what rails are as the unit only has a single 12V rail. The comm port is the connection to the Corsair Link cable. There is also a self-test button on the front. This allows you to test the unit without connecting it to any components. Just plug in the power and press the button. If the light goes green, it is good to go. Otherwise, it will go red to let you know there is a problem.

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Flipping over to the bottom we find the 140mm fan that provides cooling for the AX1200i.

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The AX1200i is fully modular. All cables are either fully sleeved or of the flat ribbon type.

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Rounding out the contents of the box are the AX1200i user manual and the paper telling you where to go download the latest version of the Corsair Link software. It would be nice to see them include a copy of the software on the flash drive since the text file only takes up 249KB of space.

Cabling Arrangement and A Look Inside

Cabling Arrangement

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Corsair does a great job with cable and connector availability for the AX1200i. Not counting the Link cable, there are 18 cables that provide one Main, two EPS12V, six PCI-E, 16 SATA and 12 Molex connectors. This is a tad different from the original AX1200 and the difference lies in the SATA cables. Previously there were three long and two short SATA cables. This time around, Corsair ditched the two short cables and gave us one extra-long cable. It is a shame to see those two short cables go as they were great for running to the top of the case for a single optical drive.

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Rail distribution is as simple as it gets on the surface with a single 12V rail. This can change with the Corsair Link software as you can essentially turn each PCI-E cable into its own rail and manually set the OCP trip point individually and up to 40A. For our testing purposes, we don't need to worry about setting individual trip points and will be testing it as a single rail power supply.

A Look Inside

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Cracking open the AX1200i we see that there have been some subtle changes made superficially with the reduced number of components. These changes result in less heat generation and increased efficiency.

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Corsair claims to have gone all out with the transient filtering stage on the AX1200i and that seems to be true. The AC input starts the filtering with the EMI filter being built in.

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More filtering continues on the PCB would the capacitors and coils. Multiple MOVs are present to help with surge suppression as well.

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A pair of Panasonic caps covers the primary side of the Corsair AX1200i 1200W PSU. No amount of lighting and focus trickery could get us a good shot of the secondary capacitors, but they are made by Rubycon giving the AX1200i 100% Japanese capacitors all the way around.

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Above is the heart and soul of the new AX2100i, the DSP or Digital Signal Processor. We could try and explain this to you, but Corsair blogged about it at launch and did an amazing job explaining it. Below is a quote about the DSP:

"The part of the AX1200i that makes it unique versus other desktop power supplies is the absence of a PFC/PWM controller IC (integrated circuit) and a supervisor IC. Both of these parts have been replaced with DSP, which stands for "Digital Signal Processor". The AX1200i power supply still uses a resonant mode topology like a lot of modern day super-efficient power supplies, but typically in other PSUs a PWM controller IC changes the power supply's switching frequency based on an analog signal derived from the load measured at the transformer. This makes the power supply more efficient at a wider range of loads compared to other power supply topologies, but it can affect ripple and noise and voltage regulation. In some power supplies, a supervisor IC will monitor voltages via a "sense wire" at the load, in an attempt to improve voltage regulation. This information is sent back to the PWM controller via an analog signal, but this information moves relatively slow when compared to the ever-varying loads of your typical PC, so voltage regulation is still not as good as it can be.

The AX1200i improves on this analog system, by using it's DSP to calculate measurements collected digitally from throughout the power supply (AC input, load on the transformers, the DC load and output voltage, etc.). This information is then analyzed by the DSP's microprocessor and adjustments are made to the different components of the power supply that improves efficiency while maintaining very tight voltage regulation and minimizing ripple and noise. Because the signals are digital instead of analog and a DSP is used to analyze the information as opposed to relatively simple ICs, adjustments can be made much faster than can be made with the typical set of ICs found in other desktop power supplies."

Essentially it allows the power supply to monitor changes faster which then results in faster corrections being made. The end result is tighter voltage control with improved DC output quality and increased efficiency.

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Cooling for the unit is provided by the Yate Loon D14BH-12 fan. This fan is PWM controlled which allows for better efficiency and lower RPM operation. Note the extra wire in there that is taped in place. This is an intake air temperature sensor that feeds information to the DSP.

Corsair Link Hardware and Software

Aside from the DSP, the other big feature of the AX1200i is the inclusion of Corsair Link to monitor and control the power supply. The Corsair Link Dashboard software is designed to allow you to monitor and control all aspects of your computer and can be connected directly to other pieces of Corsair Hardware inside your case such as the H80 cooler or the new Dominator Platinum DDR3 memory kits.

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Since we are just using the Corsair Link software to monitor the power supply for now, we can use the included USB dongle to connect to the power supply. If you're using more than one device, you might want to look into utilizing the Corsair Link Commander which allows multiple devices to be connected to it.

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Installation of the dongle was as simple as plugging it into an open USB header on the motherboard. Drivers were automatically installed. After downloading and installing the latest version of the Corsair Link Dashboard software, we gave the computer a reboot and were ready to go.

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Upon launching the software, we are given a blank slate to start defining our layout and configuration.

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You can select from several different cases so that it matches your system. In the event that you don't have one of the preloaded cases, you can upload a custom image for the software to use.

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Out of the box it picks up several temperatures right away. As you can see, it is monitors the current CPU and GPU as well as the SSD. You can create groups as well in the event that you have multiple items installed or want to monitor a specific area of the case. This is nice if you have multiples of the same type of hardware, say video cards or processors, so that they can been seen simultaneously.

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If you prefer to monitor things over time you can go to the graph mode and see this as well.

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There are several options to configure, including whether you want to display temps in Celsius or Fahrenheit, skin color and mail options for alerts.

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Adding in the AX1200i to the monitor increases the graphs for you to look at.

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Once the AX1200i is available, there is a new tab at the top for power. This will give you full monitoring over the power supply including efficiency, power usage, voltages, amperages on each rail and more.

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The window scales quite well when stretched out. Here we have also enable the OCP on all of the PCI-E rails even though no power is being drawn from them.

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You can even open different panels on the left while you are making changes to continue monitoring your system. All in all, Corsair has done a great job with the Corsair Link Dashboard software. When utilizing several of Corsair's products in a single system, you can quickly and easily achieve a vast amount of monitoring and customization that was previously unavailable without a substantial amount of custom modding.

Test Results and Final Thoughts

Test Results

Our load tests utilize a couple of FAST ATE active load testers and a variety of other equipment such as an oscilloscope, power conditioner, temperature probe and a power consumption meter. You can read more about our standard testing approach here.

The tests performed are based around six conceivable setups that are out there and progressively load down the PSU up to the power supply's limits or 1000W, whichever comes first. Since our test equipment's limits are lower than that of the Corsair AX1200i, we can only test it to 1000W.

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Let's start by taking a look at the voltages to see how well this unit did during testing. Starting with the 12V rail, we see 1% regulation from start to finish. The 12V rail showed a total drop of .10V from start to finish. The 5V rail did just as well as it managed to stay within 1% of specification with a total drop of .06V from start to finish. Moving towards the 3.3V rail, we see that regulation was still within 1% with a total voltage drop of .05V.

DC output quality was what were hoping for and even better than the previous AX1200. We started off seeing 4mV of ripple on the 12V rail during Test 1. As we increased the loads, the ripple had increased to 9mV at a little under half load. By the time we had the maximum load of 1000W we were seeing 14mV of noise.

The Corsair AX1200i is rated for 80Plus Platinum efficiency which is a step up from the previous rating of Gold for the original AX1200 unit. This means that the power supply must perform at 90%/92%/89% efficiency at 20%/50%/100% loads respectively. As you can see, the Corsair AX1200i passed on our bench wasn't close to failing at any point.

Final Thoughts

One thing is very clear when you start to look at the new AX1200i and that is we can't simply judge it based upon performance and build quality. The integration of the unit into the Corsair Link hardware and software represents a huge shift in what enthusiasts are going to want and be able to do with their power supplies. As such, we have to take a look at both pieces separately and then again as a whole.

Looking at the performance of the AX1200i, we simply can't find enough things to say about the unit. Voltage regulation was the best we have ever seen in any power supply. We've had other units that would have one or more rails perform within 1% of specifications, but never all the rails on the power supply. It is simply unheard of and Corsair has done an amazing job with this. It doesn't stop there though as the DC output quality is also the best that we have ever seen. We wouldn't be nearly as shocked and surprised if this was a mid-range unit pumping out 700W or so, but keeping the noise down so low on a 1200W unit is amazing. The AX1200i is also at the top of our list for efficiency. The last year and a half has shown a surge in Platinum rated power supplies, but the number of them that can output over 1000W can still be counted on your fingers.

The build quality of the AX1200i is also superb. As you would expect, the power supply features 100% Japanese capacitors throughout. Another big piece of the puzzle is that Corsair is confident enough to back the power supply by their industry leading seven year warranty. To the best of our knowledge, Thermaltake is the only other manufacturer to offer such a warranty and it really goes to show the confidence that Corsair has in the AX1200i. The inclusion of the DSP is also a big step and you can bet that many others will be following suit soon and are now a little behind the curve.

Set all of that aside and look at what the integration of the AX1200i into Corsair Link means for the end user. No longer are you stuck with a fan you can't control or a fan that requires a rheostat of some sort to manage. Those that are conscious about their power consumption will now be able to tell when and where it is going. This isn't just a built in Kill-a-Watt, but you can see which connector on the power supply is drawing how much power. You can also manage OCP on individual lines. Afraid that the volt-mod on your GPU might short out and kill your whole system? No problem!

Previously the Corsair Link system was more about monitoring temperatures with fan and lighting control. Corsair has changed that quite a bit with the addition of AX1200i and the new Dominator Platinum memory. It offers a complete system for monitoring your PC and controlling other items. Add in other items from Corsair and you've got a setup for unprecedented monitoring and control over your PC that goes far beyond fan and lighting control. The performance and build quality alone make this the best power supply that we've ever had the pleasure of putting on our test bench, but the integration of the power supply into the Corsair Link system make it the best power supply we've ever seen.