CORSAIR AX1600i Digital Power Supply Review

1. Introduction2. Bundle & Cabling3. External4. Internal5. Testing Methodology & Results6. Closing Thoughts7. View All Pages

Today we are looking at the brand new Corsair AX1600i Digital Power supply, an expensive $500 high end unit set to target the wealthy enthusiast audience who simply need the highest levels of quality power. Corsair say this is their most efficient and powerful supply to date – this flagship unit delivers 80 Plus Titanium efficiency and incorporates high grade 105c Japanese capacitors throughout.

Corsair are keen to point out that silicon is ‘so 21st Century' – they are moving to Gallium Nitride. As they told us ‘Originally, silicon was the ideal material for transistors because of its electrical properties and low cost compared to the old vacuum tube. But just as Moore's Law predicted, there is a need to double the transistor's performance while lowering costs. As the need for better performance increases, the ability for silicon to deliver is reaching the end of the road. The switch from silicon to Gallium Nitride (GaN) solves this problem as Gallium Nitride has lower resistance and faster switching, resulting in less switching losses, less capacitance and 40% more power density than silicon counterparts.'

We will look a little more into this when we open the supply later in this review.

The official Corsair specifications table shows that the AX1600i is $50 more expensive than the AX1500i flagship before it. Corsair has however managed to shrink the length of the power supply by 20mm, boost heat dissipation and increase the rated power delivery by 100 watts.

You get the same high level 10 year warranty as the AX1500i, which is only surpassed by the industry leading 12 year Seasonic warranty. Pricing is going to ensure this is niche unit strictly targeting the ultra high end audience. Currently the AX1500i is £439.99 in the UK, so the AX1600i will likely be in excess of £450 when it hits the UK.

Features:

• 1600W of Ultimate Power: Delivers 1600W of continuous, ultra-stable, 80 PLUS Titanium efficiency power.
• Top Tier Components: 100% 105°C Japanese capacitors, top-specification internal components and digital design deliver over 94% efficiency.
• The Only Consumer PSU with Gallium Nitride Transistors: Totem-pole PFC Gallium Nitride (GaN) transistors for superior efficiency in a smaller form factor.
• World Class Electrical Performance: Incredibly stable voltages and ultra-low ripple noise.
• Software Monitoring: CORSAIR LINK software provides in-depth monitoring for PSU temperature, fan speed, voltages, current, AC/DC wattage and efficiency, with the ability to log everything for easy troubleshooting.
• Take Control: CORSAIR LINK lets you adjust cooling fan speed, RPM curves and switch between single or multi-rail overcurrent protection (OCP), all from your desktop.
• 140mm Patented FDB cooling fan: Delivers low-noise operation even at demanding loads.
• Zero RPM Fan Mode: For near-silent operation at low to medium loads.
• Choose Your Color: Three-color customizable magnetic side labels let you choose your PSU’s style to match your build.
• Fully Modular Cables: Use only the cables you need for quick and easy installation
• Built to Last: Ten-Year comprehensive CORSAIR warranty.

Review photography handled in house at KitGuru with a Leica S series medium format camera and S series prime lens. Please do not use any of the images within this review without express permission.

The Corsair AX1600i Digital power supply ships in a large, heavy box featuring an image of the power supply on the front, along with simple, yet effective yellow accents. Corsair highlight the 10 year warranty, Titanium efficiency, Zero Fan configuration and the Digital Link feature.

The rear of the box goes into a little more detail. I like how Corsair show photographs of the cabling along the top of the box – making it really handy to check if you are browsing in a physical retail store (some people still use those, right?).

Inside the box, Corsair include coloured stickers and some user literature on the product. A very nifty idea to solve the problem of the default stickers clashing with a colour coordinated system build.

The AX1600i is well protected during shipping. It is sandwiched between two thick pieces of foam and protected against scratches inside a black felt bag.

Corsair also supply a regional specific C19 power cable, felt cable ties and mounting screws. They also supply what appears to be a bag of cables, but its much more than that.

This is not merely just a storage bag, its a compartmentalised rolled up storage pouch with all the cables clearly marked in sections. Almost like a tool kit bag I bought last year from WIHA. I love this idea, so kudos and bonus points to Corsair.

If you want to run a high end render system with multiple graphics cards, this power supply should surely be making your final shortlist. Its worth pointing out that Corsair have changed some of the cables since the AX1500i was launched. The AX1600i is equipped with new ‘Type 4' cables.

The 6 pin cables for SATA and peripheral power are the same as the Type 3 cables used with the HXi, RM supplies. The 8 pin cables for the ATX12V/EPS12V and PCIe are pin compatible with Type 3 cables but have added capacitors to help reduce the ripple noise on the leads. The Type 4 24 pin cable has an additional 4 pins – these are ‘sense wires' that allow the AX1600i to sense the voltage at the load and adjust on the fly to improve voltage regulation. Corsair published a lot of information on these new cables and you can read more about them over HERE.

The AX1600i is distinctive and immediately recognisable as a Corsair power supply. Its a long power supply, but its 2cm shorter than the AX1500i (22.5cm). The other measurements of the AX1600i are 86mm (H) x 150mm (W) . Paintwork is very good, with it proving resistant to light scratches. Its a well finished unit, expected at this price.

The Corsair branding gets pride of place in the centre of the unit on one side, as shown above.

The large fan is visible behind the metal grill, above. We will take a closer look at this when we open the supply later in the review.

One side of the power supply is home to the power switch and connector cable. There is a removable sticker here explaining that the supply fan will not activate at lower load demands.

The power supply needs a larger C19 power cable (supplied) as indicated by the size of the three individual power pins.

The modular panel is packed with connectors and buttons. All the connectors are labelled to make it easy during the build phase. The connectors are all different sizes so it makes it impossible to plug in the wrong connector.

In Multi Rail mode, the +12V rail is split into twelve separate +12V rails, each with a default OCP of 40A. In Link, this OCP can be adjusted from 0A to a maximum of 40A.

The Corsair Link connector is useful, as you can monitor efficiency, voltage regulation and it allows you to change fan speeds and individual over current protection points on each connector.

With the 24 pin cable removed from the connector, the ‘self-test' button tests the functionality of the power supply. If the PSU passes the self test then the LED on the left (under the word ‘SELF) will light up green.

The LED on the left represents USB data communication. Once the USB cable is attached to the motherboard the LED will illuminate green. Once data communication is enabled between the power supply and the LINK software the LED will switch colours between green and amber to show you that the communication is working fine.

Corsair Link software will be known by some of our readers already — it offers control over the power supply, including changing it from Single Rail to Multi Rail, and back again. In Multi rail +12V rail mode each PCIe output connector can have its OCP trigger point set. Additionally the SATA and Molex connectors have their own OCP as well as the +12V on the 24 pin.

The AC power in and DC power out can be monitored from the software and the efficiency level will get automatically calculated. It is possible to monitor the +3.3V, +5V and +12V rail voltage as the internal temperatures and fan speed. Those who like to create custom fan profiles will be happy to hear that the software allows for this as well.

CORSAIR AX1600i Digital Power Supply Review
DC Output	+3.3V	+5V	+12V	-12V	+5Vsb
Max Output	30A	30A	133.3A	0.8A	3.5A
Total Power	180W		1600W	9.6W	17.5W
	1600W

The single +12V rail can deliver 133.3A which is a crazy amount of power. Its true that many gaming systems today will never need close to 1600 watts, but we thought this might be a good time to take a (funny) trip down memory lane !

‘With this kind of juice on tap there would be no problems powering even two overclocked AMD R9 295X2. Our previous review of the OverclockersUK Infinity Vesuvius system highlighted that two R9 295X2 cards could demand close to 1,200 watts under load.'

Good times from 2014!

Obviously in 2017 this kind of power delivery will be specifically useful for miners and perhaps render stations with multiple GPU's. Those people running systems with two GTX 1080ti's will be likely only hitting around 600-700 watts under load.

The 140mm fan is branded with a Corsair sticker (model number NR140P). We know this fan incorporates fluid dynamic bearings. The fan is rated to a maximum speed of 1,800 rpm / 0.22A (2.6 watts) at 12 VDC. It is the same fan that was in the AX1500i.

The MTBF of the fan is said to be greater than 100k hours. Corsair use their ‘Zero RPM' system which means that the fan won't even rotate under low to medium loads. Medium load for a 1600 watt power supply is quite a lot.

Example? Well we recorded a tiny, barely active 500 rpm fan speed at 800 watts, which is incredible. At 600 watts the fan was disabled completely so its basically as quiet at the Seasonic Prime Titanium Fanless 600 watt unit that we reviewed in December 2017.

If you can’t see the image gallery above then you will need to whitelist us or disable your ad blocker – they can interfere with our specialist display code.

The design is using a bridgeless totem-pole PFC circuit utillising GaN power FETs from Transphorm. Regular KItGuru readers who enjoyed our AX1500i Flextronics OEM review back in April 2014 will remember that was a bridgeless, 2 phase interleaved PFC circuit. Corsair claim the Transphorm GaN totem pole PFC is 99% efficient while taking up less space on the PCB.

Inside, its an all 105c Japanese construction, always good to see. High grade Nippon Chemi Con and Rubycon are used in the primary stage. There are three main capacitors – two rated 450v 470uF and one 450v 680uF. This gives a staggering total of 1620uF. One of the highest combined uF output figures we have seen from any power supply to grace our labs.

The soldering on the PCB is immaculate and even the modular daughter card is exceptionally well finished. We can see 2 PFC chokes alongside the EMC/EMI filtering close to the AC socket. Along one side of the PSU is a control board – DSC primary, 1x MCU and 1x DSC secondary. In front of the modular connector board is the +12V output wire with ferrite core to reduce ripple and noise. Along the other side of the supply is the +5V and +3.3V DC to DC converter board.

AX1600i Safety Protections
AX1600i has the necessary protection functions to ensure trouble-free operation, even in extreme conditions. Below is a list of the included protections:

• Over Current Protection (OCP): Shuts off power if any rail is overloaded beyond a safe level.
• Over Voltage Protection (OVP): Shuts off power if voltages exceed specification.
• Under Voltage Protection (UVP): Shuts off power if voltages drop below specification.
• Short Circuit Protection (SCP): Shuts off power if a short circuit is detected.
• Over Temperature Protection (OTP): Shuts off power if temperatures exceed a specified value.
• Over Power Protection (OPP): Shuts off power if the total output power exceeds a safe level.

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
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We test in single rail mode.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
150W	0.88	3.34	0.84	5.03	11.60	12.09	0.5	5.01	0.20	-12.03
300W	1.62	3.34	1.63	5.03	24.02	12.08	1.0	5.01	0.20	-12.03
750W	3.00	3.34	3.06	5.03	60.21	12.04	1.5	5.01	0.30	-12.03
1125W	4.00	3.33	4.07	5.02	90.00	12.03	2.0	5.00	0.30	-12.04
1500W	15.79	3.33	15.56	5.02	113.90	12.02	2.5	5.00	0.50	-12.04
1600W	9.23	3.33	9.12	5.03	126.60	12.00	3.0	5.00	0.50	-12.05

Load regulation is class leading, even when delivering the full 1600 watts of power.

CORSAIR AX1600i Digital Power Supply	Maximum Load
	1808W

We managed to get the PSU to achieve 1808W before it would shut down, delivering around 208W more than the rated specifications. It shut down safely when we pushed it beyond the limits and was ready again for a more sensible demand.

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
1150W	3.0	3.34	2.0	5.04	92.0	12.04	0.2	-12.03	0.50	5.01
250W	20.0	3.33	24.0	5.02	5.0	12.08	0.2	-12.03	0.50	5.01

The Corsair AX1600i 1600W produced some stunning results in the cross loading test. No discernible weaknesses at all.

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
500W	5	5	10	5
750W	5	5	10	5
1000W	5	5	10	5
1250W	5	5	10	5
1500W	5	5	15	5
1600W	10	10	15	5

Class leading ripple suppression peaking at 10mV on both +3.3V and +5V rails. The +12V rail peaked at 15mV. Stellar results all round for the AX1600i.

Efficiency (%)
500W	95.21
750W	97.31
1000W	96.78
1250W	96.21
1500W	95.79
1600W	95.11

Overall efficiency is excellent, peaking at 97.3% when delivering between 750 and 850 watts. At full load we recorded an efficiency of 95.1% which is remarkable.

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 Digital Sound Level Noise Decibel Meter Style 2 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)
500W	/
750W	28.3
1000W	29.7
1250W	31.4
1500W	33.3
1600W	34.1

Thanks to the extremely high efficiency of this power supply and the high grade fan the unit never emits much noise at all, even under high 1000 watt+ loads. At lower loads (anything at 600 watts or lower) the fan didn't spin at all. That's the Corsair Zero RPM working its magic.

Temperature (c)
	Intake	Exhaust
500W	36	39
750W	37	42
1000W	42	47
1250W	46	51
1500W	48	54
1600W	51	60

The large fan is inactive until about 650 watt load when it comes into action, spinning very slowly. At 100% load the fan was spinning around 1,200 rpm – which is still rather slow spinning.

Maximum load	Efficiency
1808W	94.72

At 1808W, the efficiency level is still good, measuring 94.72%. Not a practical situation to be running 24/7, but worth noting.

The CORSAIR AX1600i Digital is a remarkable power supply. The high levels of finish are complemented by the supreme engineering inside. Let's not beat about the bush, It is one of the finest power supplies we have tested.

Corsair have certainly invested time into implementing the design with the OEM. Internally no corners have been cut and Corsair are clearly keen to drive forward their reputation as one of the market leaders in 2018. The switch from silicon to Gallium Nitride (GaN) ensures that the unit can reduce switching losses while offering high levels of power density and reduced capacitance.

The new AX1600i is not just a simple iteration over the AX1500i we reviewed years ago. They have moved from a bridgeless 2 phase interleaved PFC circuit to a new Transphorm GaN totem-pole PFC design which claims up to 99% efficiency while reducing physical space on the PCB. The AX1600i is still a physically large power supply, but it is 20mm shorter than the older AX1500i.

The Corsair Link software will appeal to the high end audience who love to tinker. There are plenty of power and monitoring settings to tweak. Users can monitor the AC power in and DC power out. +3.3V, +5V, +12V rail voltage can be monitored along with internal temperatures and fan speeds. You can even create your own fan curves if you aren't happy with the Corsair default settings. The option is there to adjust OCP trigger points on the PCIe Connectors, Molex/SATA connectors and the +12V on the 24 pin.

First impressions are positive. The bundle is great, and I love the coloured stickers to suit different looking system builds, along with the rollable storage pouch for the cables. The finishing of the supply is first class – the paint is deep and it proves resistant to scratches.

Technically we can find no fault with the unit – it delivers a staggering 133.3A across the +12V rail to handle the most demanding multi GPU enthusiast builds. Internally, the use of Rubycon and Nippon Chemi Con 105c Japanese capacitors is reassuring – both for quality of power and longevity. Ripple suppression and load regulation rate very highly and cement the view that this is a power supply which will deliver the highest quality power for a long time.

We noticed that the fan didn't spin at all until around 630 watts was demanded from the unit. Under many situations this unit will actually be running passively or with the fan spinning around 400 – 700 rpm. Its an extremely quiet unit and we could barely hear it running at all with a high 1000 watt load. At 100% load (1600 watts), the fan is spinning at a modest 1,200 rpm.

We know you want this unit, but do you need this unit? Realistically, its highly unlikely. The price point alone is going to alienate most of the audience reading this review. Not many will be spending in excess of £450 on a power supply. Most of us may want the AX1600i, but its targeting a niche audience.

As an engineering and marketing exercise Corsair have totally nailed it. For the ultra high end audience this is an ideal power supply as the foundation for a new mining rig or high end workstation. If you think this is expensive it is worth pointing out the AX1600i is half the price of the Cooler Master Masterwatt Maker 1200W power supply which we analysed back in March this year (review HERE).

The only slight negative I could point at would be the 10 year warranty. Its not a complaint, but more an observation that Seasonic are still leading the market with their 12 year warranty, introduced earlier this year. 15 years would have been a real statement from Corsair around the release of this unit.

Right now we have no store links, but the AX1600i price point is set at $499. The AX1500i is currently available for around £430 (HERE). We would therefore take an educated guess that the AX1600i will cost in excess of £450 when it hits UK shores.

UPDATE 9th January 2018: You can buy from Overclockers UK – preorder price is £439.99 inc vat HERE. If that stands, then its a little less than expected.

Pros:

• Stellar power delivery.
• very quiet (silent at 600w or less).
• quality finish.
• ripple suppression.
• load regulation.
• 105C Japanese caps throughout.
• delivered over 1800 watts before shutdown.
• 10 year warranty.

Cons:

• Very expensive.
• Seasonic warranty is still the market leading – at 12 years.

KitGuru says: If you value having the highest quality power driving your system then the CORSAIR AX1600i stands high in a class of few others. For the ultra high end target audience, it is surely a wise choice.

Become a Patron!