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Corsair AX1200i Digital ATX 1200-watt Power Supply Review

By: Chris Ramseyer | Other PSUs in Cases, Cooling & PSU | Posted: Aug 3, 2012 7:23 am
TweakTown Rating: 96%Manufacturer: Corsair

Cabling Arrangement




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.




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




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.




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.




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




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.




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.




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.

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