Corsair Professional Series AX1200i Power Supply Review

1. Introduction2. Corsair Professional Series AX1200i (Bundle & Cables)3. Corsair Professional Series AX1200i (External)4. Corsair Professional Series AX1200i (Internal)5. Corsair Professional Series AX1200i (software)6. Corsair Professional Series AX1200i (Super High Res Gallery)7. Testing Methodology and Results8. Closing Thoughts9. View All Pages

Today we look at the latest power supply from Corsair, the Professional Series AX1200i. This is the first desktop power supply to use a digital signal processor (DSP) to digitally control the power output. Corsair class the AX1200i as the ‘ultimate performance power supply for a dream PC system'. This fully modular design has over 100A available via the +12V output and has achieved 80 Plus Platinum certification.

Is this the best power supply that money can buy?

Product Overview:

• Digitally Controlled Power.
• 80 Plus Platinum Efficiency.
• Ultra Low Noise Design.
• Low Ripple and Noise: Up to 3x better than the ATX Spec.
• 100.4 Amp Single +12V Rail.
• Corsair Link Interface.
• Self Test Switch.
• Fully Modular Cable System.
• Reliable 105c Capacitors.
• 7 Year Warranty.

Very dramatic artwork from the Corsair team, focusing on a moody, angled shot of the fan on the power supply. The company mention the Platinum certification with some key points listed bottom left of the box.

The outer shell of the box is a gatefold design with some information on the cabling and a semi transparent view of the design. The inner box contains a selection of peripherals along with the main unit.

The bundle contains a user manual, Corsair chassis badge, large felt bag of modular cables, cable tidies and mounting screws.

Corsair also include a Corsair LINK interface module, which is connected to the power supply for direct access. This is a ‘server-inspired' diagnostic tool which can record and monitor real time efficiency, power usage and adjustment of the fan profiles. The power supply can also be configured as a multi rail device with individual PCI-E over current protection trip points. More on this later in the review.

Corsair bundle a series of high grade 18AWG cables with this unit, some of which are sleeved. The peripheral cabling are all flat ribbon style which will help maximise air flow throughout the chassis.

Above a list of the cables including the length. The main chassis is a pure modular design, so no cables are hardwired.

Corsair include two EPS/ATX12V 8-4 pin cables and six 6+2 pin PCI-E cables. All of the cables are long enough to work inside a large full tower case.

I do love the Corsair style of finish. Pure black with attractive two tone product stickers on either side of the chassis. The paintwork is resistant against fingerprints and is difficult to mark. We ran a screwdriver down one side of the chassis with a little force and it didn't mark at all.

Corsair are using a large 140mm fan in this unit, which is hidden behind a metal grill and company badge in the center. We will take a closer look at this when we open up the chassis.

One side of the chassis is honeycomb vented to help improve air flow around the components. At the side is a power switch and connector.

The modular panel takes up the full area of the other side of the power supply. All of the ports are clearly labelled to make the system installation phase as painfree as possible. There is also a self test button and a ‘comm port' which is used for Corsair Link connection.

The AX1200i can deliver 100.4A to the +12V rail, which is more than enough for even the most demanding multi GPU system configurations. The total power output is rated to 1204.8W.

The AX1200i incorporates a quality 140mm Yate Loon fan (D14BH-12). This fan is rated to 2,800 rpm, producing 140 cfm @ 48.5 dBa at full speed. We wouldn't imagine there is any need to get anywhere close to these rated specifications. We have seen this fan used in some other high grade power supplies this year.

This looks to be a Flextronics design. The AX1200i is jam packed from edge to edge with several rows of black heatsinks handling heat transfer. The design uses a DSP which reduces the overall number of discrete components. This reduced component count has the benefit of reducing losses in the circuit and helping to improve efficiency. Corsair also say that this reduction helps improve reliability.

The AX1200i uses Zero Voltage Switching and Zero Current Switching (ZVS/ZVC) technology to switch at near 0V and 0A.

The AX1200i features DC-DC regulation for 3.3V, 5V and 12V rails and secondary side rectification. The supply uses a 4 layer modular connector board PCB to help improve the ground return plane with lower resistance and low voltage drops.

The design uses 105c rated capacitors throughout, include a pair of Panasonic- 470uF, 450V in the primary stage.

One of the main talking points with this latest AX1200i Power Supply is the connection with the Corsair Link Dashboard 2 software. This can be downloaded directly from the Corsair website.

Above, the Corsair Link dongle has to be hooked into the power supply and then connected to a free USB port on the motherboard. All the cables are supplied in the box.

Above, an overview of the main software panel. The software defaults to a Corsair case, however you can upload an image of your own, or use another of the presets. It uses the temperature sensors of connected devices to give a list of everything attached. We used a Solid State drive so the HDD Temp1 variable didn't show.

Above an overview of some of the other panels included with the software package. If the USB dongle isn't connected correctly, then the ‘power tab' won't show.

Above, an overview of the power menu which we lifted from the Corsair V2 beta user guide. The top area (marked 1) in this, shows real time efficiency levels. On the left is the actual efficiency, and on the right is a graph that shows it as it changes. This is calculated from the power input and power output displayed in section 2.

Corsair say that accuracy swings might sometimes cause inaccurate results, such as 80% or 100%. This is a limitation of the monitoring technique rather than a problem with the power supply.

There is also a real time power section which gives a rough indication of how much power the system is draining at the socket.

There is also a voltage regulation and power draw section underneath (4) which highlights the current voltage regulation on the 24 pin, +12V rail, AC Input (MAIN), peripheral +12V connectors (SATA and Molex) and the 3.3V and 5V rails. Corsair claim that voltage regulation is accurate to within 2% either way.

Section 5 at the bottom is the over current protection section. The AX1200i by default is set to a single rail implementation, although you can manually override this to independent +12V rails. You can adjust the connector OCP point between 20A and 40A – per connector (not per device).

On this page we present some super high resolution images of the product taken with the 24.5MP Nikon D3X camera and 24-70mm ED lens. These will take much longer to open due to the dimensions, especially on slower connections. If you use these pictures on another site or publication, please credit Kitguru.net as the owner/source.

Additional technical assistance: Peter McFarland and Jeremy Price.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. Due to public requests we have changed our temperature settings recently – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 35c) in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa)
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
330W	5.59	3.39	5.55	5.07	21.23	12.18	0.85	5.06	0.20	-12.04
620W	11.07	3.37	11.08	5.04	42.54	12.14	1.74	5.04	0.40	-12.05
918W	16.58	3.35	16.45	5.03	63.75	12.09	2.64	5.03	0.60	-12.08
1204W	22.04	3.33	22.04	5.00	85.03	12.05	3.6	5.02	0.80	-12.12

Corsair Professional Series AX1200i	Maximum Load
	1324W

We managed to get 1324W from the unit before it would switch off. The over circuit protection system worked well and it shut off safely.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing	+3.3V		+5V		+12V		-12V		+5VSB
	A	V	A	V	A	V	A	V	A	V
1190W	4.0	3.37	3.0	5.06	88.0	12.04	0.20	-12.04	0.50	5.04
195W	19.0	3.33	22.0	5.00	2.5	12.13	0.20	-12.03	0.50	5.03

The Cross loading performance is excellent. We hit the supply with 88A on the +12V rail and it held at 12.04v. Other rails exhibited class leading results.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum.

ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output	Ripple (mV p-p)
+3.3V	50
+5V	50
+12V1	120
+12V2	120
-12V	120
+5VSB	50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load	+3.3V	+5V	+12V	5VSB
330W	5	5	10	10
620W	10	10	15	10
918W	15	10	20	15
1204W	25	20	25	15

Noise suppression is fantastic. The +12V rail peaked at 25 mV under full load. The +5v rail peaked at 20mV and the +3.3V rail peaked at 25 mV – not class leading results, but still well within tolerance specifications.

Efficiency (%)
330W	90.68
620W	93.67
918W	92.63
1204W	91.45

Efficiency is excellent, peaking at 93.67% when under 50% load. Efficiency drops to 91.45% at full load. Excellent results.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the Power Supply we have taken it into our acoustics room environment and have set our SkyTronic DSL 2 Digital Sound Level Meter (6-130dBa) one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refrigerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
330W	<28.0
620W	<28.0
918W	32.2
1204W	34.7

The fan didn't spin up until around 40 percent of system load, although it wasn't really audible until around a 900W load was placed on the system. At full load it was still surprisingly quiet, measuring 34.7 dBa via our noise metering equipment.

Temperature (c)
	Intake	Exhaust
330W	35	38
620W	38	44
918W	42	48
1204W	45	54

At full load, the ambient temperatures are well maintained, with a 9c variable on exhaust.

Maximum load	Efficiency
1324W	90.2

Pushing the PSU above its rated limits generates an efficiency level of around 90.2%. This is not a viable ‘real world’ situation, but its interesting nonetheless.

Corsair power supplies have earned a great reputation over the years, and the Professional Series AX1200i is their best to date, which in itself is quite an achievement.

Aesthetically, the unit is finished to the highest standards, something we expect from Corsair. The paintwork is resistant to scratching, and it doesn't attract fingerprints either.

The bundle is exemplary and contains a wealth of little extras which add value. The Corsair Link interface module is certainly a talking point and it will appeal to the high end enthusiast audience who love to spend time tweaking their systems. The option to adjust from single rail to independent rails for devices is certainly welcomed … between 20A and 40A per connector.

Technically, the unit doesn't fail to deliver. It delivers rock solid load regulation and it handled our intensive cross loading tests with relative ease. Ripple suppression is impressive, particularly via the +12V output, which peaked at 25mV under full load conditions. +3.3V and +5V rails weren't quite as impressive, but they fell well within rated ATX tolerance specifications.

Corsair have always tried to deliver class leading acoustic performance from their high end power supplies and in this regard the AX1200i is a success. The non aggressive fan profile doesn't really kick in until around 900W of total load, and even then it never becomes intrusive, likely drown out in the real world by several quality chassis fans.

We hope Corsair release more of this digital range in the coming months, because while the AX1200i is a powerhouse supply, at £260 inc vat it will be priced outside the budget confines for 95% of the enthusiast audience.

Pros:

• Technically very proficient.
• No regulation weaknesses.
• quiet.
• beautifully finished.
• excellent bundle.
• interactive software suite adds value.
• full modular design.
• high grade cabling.
• 7 year warranty.

Cons:

• At this price, it is only for the wealthy enthusiast audience.

Kitguru says: A fantastic power supply from Corsair which cements their position in the high end sector.

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