Corsair HX850 Platinum (2017) Power Supply Review

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

Today we analyse one of the latest power supplies from fan favourite Corsair. I last looked at the HX range back in 2012 but Corsair have updated the newest HX model in key areas – its now a pure modular design with efficiency levels enhanced from Gold to Platinum levels. The HX range is also equipped with a +12V Rail selection to switch between single and multiple +12V rail modes.

Corsair are releasing four new HX power supplies in 750w, 850w, 1000W and 1200W capacities. They sent us the HX850 model which proved one of the most popular output capacities with our readers in a recent poll on social media.

While it is confusing enough to have a new updated model with the same ‘HX' moniker as before (Platinum page is HERE, older Gold page is HERE), Corsair complicate matters by having similar ranges available. The RMx series for instance is a 80 Plus Gold certified, fully modular range incorporating a 135mm rifle bearing fan inside.

The HXi range of power supplies (Platinum rated) are priced a little higher (£10-£15 more) than the plain HX series we look at today but they incorporate full Corsair Link Support. This is a popular feature with many enthusiast users as they get Windows OS support to control fan speeds via all their Corsair components and can even monitor various aspects of the power delivery. If you feel this is superfluous then you can save a little bit of cash and get the plain HX Platinum unit.

All of the HX, RMx and HXi come with a very impressive 10 year warranty. Its not quite at the same 12 year level as Seasonic, but it is still a very long time to keep a power supply in operation. Corsairs' adoption of 105c rated Japanese level capacitors is giving them plenty of confidence with the longevity of their products.

Corsair HX Platinum Series features:

• 80 PLUS® Platinum efficiency, delivering 90% energy efficiency at real world load conditions.
• ZeroRPM mode for fanless operation at low loads and outstanding noise reduction.
• 135mm thermally controlled, fluid dynamic bearing fan only spins up as needed.
• Fully modular cables for easy installation, less clutter, and helps maximize airflow through your computer’s chassis.
• Engineered to meet maximum power output at a server-grade 50°C temperature rating.
• Over-voltage protection, under-voltage protection, short circuit protection, over power protection, and over temperature protection provide maximum safety to your critical system components.
• Safety and Agency Approvals: FCC, ICES, CE, UL / CUL, CSA, C-Tick/RCM, TUV, CB, CU, KC Mark, RoHS, WEEE, RoHS (China), REACH

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 HX850 ships in a dark box with bright yellow accenting. The front highlights the capacity, 10 year warranty and new Platinum efficiency levels.

Inside the box, alongside the power supply is a user manual, regional specific power plug, warranty guide, and a soft bag of modular cables. Corsair also include some cable ties, case badge and mounting screws.

The power supply itself is well protected inside a soft cover and is sandwiched between thick pieces of foam.

This power supply is a pure modular design so all the cables, including the main ATX cable are in the black felt bag inside the box. There are a mixture of sleeved (PCIe/CPU/ATX) and ribbon style cables (peripherals) included. Corsair include an ATX cable, two EPS connectors, a single floppy connector, 6 Molex connectors, 8 SATA connectors and 6 PCIe connectors.

The HX incorporates new ‘Type 4' cables. The 8 pin cables for EPS 12V, ATX12V and PCIe have added capacitors to help reduce ripple noise via the cables. The Type 4 24 pin has an additional four pins. These are sense wires which allow the HX supply to sense the voltage at the load and adjust accordingly to improve voltage regulation.

The table above shows all the cable configurations across the new HX Series of power supplies. I feel 6 PCIe connectors (across three cables, with two on each cable) is more than enough and will easily sate the demand for multiple graphics cards. I always like to see a mixture of straight and 90 degree angled SATA connectors, as it can help the build phase in some chassis.

The Corsair HX850 is a simple looking, yet effective monochome power supply which will cleverly fit into any colour scheme of build you can think of. Build quality is high, as we would expect, and the paint work is quite deep and doesn't scratch easily.

It measures 150 mm x 86 mm x 180 mm and weighs 1.95kg.

A large offwhite coloured fan can be seen behind the metal grill on the top of the unit. The Corsair badge can be seen in the middle. I would imagine they are using another NR135P fan, but will get a better look when we open the unit shortly.

This unit has a ‘Zero RPM' mode. At up to 40% of the PSU's maximum load with a 25c ambient room temperature, the fan will not spin. This means when idle, or low to moderate loads, noise levels will be effectively nothing.

One side of the power supply is home to the modular bay, with three rows of ports all clearly labelled for ease of use during the build.

The HX series supplies are all equipped with a single +12V Rail Selection switch which gives the user a choice of running the supply in single or multiple +12V rails. In Single mode position the full output capability of the +12V rail is available to all the connectors. In Multiple mode each individual connector has over current protection with a limit of 40A set to each cable.

Above, we can see the breakdown of the units power delivery when set to Single Rail Mode and Multiple Rail mode. We would imagine most of our readers will be using this power supply in single rail mode. It can deliver almost 71 Amps across the +12V rail at full load.

Inside the power supply, we can see Corsair are using the NR135P fan rated at 12V, 0.22A. This 135mm fluid dynamic bearing fan is made in China. There is a little piece of flexible plastic covering part of the fan – this is in place to specifically direct the airflow to specific components underneath.

This fluid dynamic bearing fan is higher grade than the rifle bearing fan we saw last week in the new TX 750M power supply.

Below - a High Resolution Gallery of the internal layout of the Corsair HX850 Platinum Power Supply

The internal build is quite clean throughout and soldering is good across the board. This design uses a lot of white fast setting adhesive, likely to help keep the components from vibrating.

Corsair are using Japanese capacitors on both the secondary and primary stages, which is good to see. The two primary capacitors are Nippon Chemi Con, 105c rated, from their high grade KMW series. Both are rated 400v 470uF, to give a total capacity of 940 uF.

As we said earlier the HX incorporates new ‘Type 4' cables. The 8 pin cables for EPS 12V, ATX12V and PCIe have added capacitors to help reduce ripple noise via the cables. The Type 4 24 pin has an additional four pins. These are sense wires which allow the HX supply to sense the voltage at the load and adjust accordingly to improve voltage regulation.

We can see the Diode bridge for AC/DC rectification of the incoming AC voltage. There is also a +3.3V/+5V daughtercard board feed from the +12V rail. The LLC main transformers is branded black with the Corsair logo in white. We can see that the plastic sheet on the fan above means the air is directed towards the SR MOSFET's, temperature thermistor and the secondary capacitors.

The power supply has the following 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. We run at 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 a single +12V configuration.

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
85W	0.95	3.34	0.93	5.03	6.03	12.09	0.50	5.01	0.20	-12.03
170W	1.70	3.34	1.68	5.03	12.40	12.08	1.00	5.01	0.20	-12.04
425W	3.02	3.34	3.07	5.02	32.22	12.06	1.50	5.00	0.30	-12.04
640W	4.07	3.33	4.04	5.00	49.00	12.05	2.00	5.00	0.30	-12.04
850W	5.00	3.34	5.23	5.03	65.60	12.02	2.50	5.00	0.50	-12.03

Load regulation is excellent with the rails exhibiting very minor fluctuation under load.

Corsair HX850 Platinum	Maximum Load
	917W

We managed to get the power supply to deliver 917W before it would shut down, delivering around 82W more than rated specifications.

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
760W	1.0	3.34	1.0	5.03	60.0	12.04	0.2	-12.03	0.50	5.01
165W	15.0	3.31	18.0	5.00	2.0	12.09	0.2	-12.03	0.50	5.00

The power supply dealt with the demanding cross load test without issue exhibiting only a little fluctuation. It was tasked with 60A on the +12V rail and it held at 12.04V. The other rails delivered excellent results also.

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
100W	10	5	10	5
225W	10	10	15	5
450W	10	10	20	5
675W	10	15	25	10
850W	10	15	30	10

Noise suppression results are really impressive, hitting 10mV and 15mV on +3.3V and +5V rails respectively. The +12V rail peaks at 30mV under full load conditions. Fantastic results overall.

Efficiency (%)
100W	87.92
225W	92.21
450W	93.44
675W	92.76
850W	91.71

Efficiency is extremely impressive, peaking at just over 93.4 percent at 50 percent load. This drops to around 91.7 percent at full load.

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)
100W	<28.0
225W	<28.0
450W	29.8
675W	32.4
850W	33.9

The large fan spins relatively slowly under most load conditions and the unit is not audible until hitting around 500 watts of power demand. In the last 300 watts of load, the fan slowly spins up to around 1,000rpm, which measured 33.9dBa by our meter.

I couldn't hear any coil whine during our tests.

Temperature (c)
	Intake	Exhaust
100W	37	40
225W	38	42
450W	40	49
675W	45	52
850W	47	58

The high levels of efficiency help keep the temperature control system operating with optimisation. Temperatures rise to only a +11 variable at full load.

Maximum load	Efficiency
917 watts	90.6

At 917 watts, the efficiency level measures 90.6%. Not a practical situation to be running 24/7, but worth noting.

Corsair's HX range of power supplies have been very successful for the company so it makes sense they release a new version in 2017 with up to date technical improvements, full modular capability and enhanced 80 Plus Platinum efficiency levels.

First impressions are positive. The unit is finished to a high standard and Corsair have been careful to omit all colour from the power supply so it can easily match any schemed system build you are planning. Paintwork is deep and it proves difficult to scratch – this is more important than you think, as I have had power supplies mark very easily, simply by sliding them into the recess inside a new case.

Technically the HX850 is very proficient and it didnt flag any noticeable concerns throughout the last week of testing in our labs. Our results highlight that load regulation is very good, and the HX850 Platinum also passed the cross load test without a hitch. Efficiency levels are high (hitting close to 93.5% at 50% load) and thanks to the new internal design and updated Type 4 cables, ripple suppression is excellent.

According to our latest polls run on the main site and on social media, the most popular power supply capacities are 650 Watt and 750 Watt followed closely by 850 Watt units. There are benefits to owning a higher rated power supply. For example, an 850 watt power supply will easily handle a high end dual card Crossfire or SLI system but it will do so with plenty of power in reserve to ensure the fan isn't running too high (think noise), and efficiency levels are close to peak between 40% and 60% of total load.

The Platinum HX850 power supply ships with plenty of cables to cover modest to high end system builds, and the pure design means you aren't left routing any cables you don't need – ideal to keep the appearance as good looking as possible.

Those of you who hate noisy power supplies will like the HX850 Platinum. The NR135P fan is basically inactive for the first half of the power delivery and when the load increases, the fan never spins higher than 1,000 rpm (at full load). The Fluid Dynamic Bearing fan fitted in this power supply is very quiet and will be likely masked by any other fans in the system build.

You can buy the Corsair HX850 Platinum direct from Overclockers UK for £154.99 inc vat HERE.

Discuss on our Facebook page, over HERE.

Pros:

• Build Quality.
• ripple suppression.
• low noise.
• fully modular.
• Platinum efficiency.
• lack of coil whine.

Cons:

• Stiff competition around the £150 price point.

KitGuru says: The Corsair HX850 Platinum is a fantastic power supply, built to the highest standards. Its fully modular, quiet, well built, and technically very proficient. Another quality unit from Corsair.

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