Corsair HX850 Gold Professional Series Power Supply review

1. Introduction2. Corsair HX850 Professional Series (Bundle & Cables)3. Corsair HX850 Professional Series (External)4. Corsair HX850 Professional Series (Internal)5. Corsair HX850 Professional Series (Super High Res Gallery)6. Testing Methodology & Results7. Closing Thoughts8. View All Pages

If you ask an enthusiast user to recommend a high grade power supply you can be sure that Corsair will normally get a mention in the shortlist. The company have worked diligently with several leading partners in the production of their power supplies and today we tear apart their latest HX850 Gold Professional – a semi modular design which boasts 80 Plus Gold Certification.

The Corsair HX850 power supply is based around a Channel Well technology (CWT) design featuring a large slow spinning fan, high grade Japanese capacitors and a class leading 7 year warranty. Corsair are keen to point out that their power supplies are not simple ‘off the shelf rebadging', as they have important engineering input on the designs.

I believe an 850W power supply is the high end ‘sweet spot', capable of handling the most demanding multi GPU systems without potentially breaking the bank. The Corsair HX850 is due for release today at a price point around £139.99 inc vat, placing it firmly in the upper cost bracket of 850W models currently available.

Key Specifications:

• Quiet Operation at low loads.
• Modular cables for easy installation.
• 80 Plus Gold: High Efficiency, low heat.
• Reliable 105c capacitors.
• 7 year warranty.

Corsair box art is always stylish, clean and beautifully presented. The HX850 makes no exception to the rule. The power supply fan is highlighted from an angled top down viewpoint.

Inside, the power supply is protected between very thick foam, and tied inside a felt bag. The modular cables ship in a handy pouch which can be reused for storage. They also supply a little user manual, screws and cable ties to improve cabling routing.

Above left, the modular cables, and above right, the hardwired cables into the chassis. The peripheral cables are flat, which can help improve system airflow, especially from the intake area at the front of the chassis.

Above, a breakdown of the cables, including their length. The HX850 Gold ships with six 600mm 6+2pin PCIE power cables, ideal for a high end Crossfire or SLI system build.

The HX850 is very nicely finished, as we would expect from Corsair. It is completely black, with a sticker on the side featuring the company name and product identity.

Corsair are using a large 140mm fan for the HX850, resting behind a black grill with company logo in the center.

One side of the power supply is honeycomb vented to improve air flow. There is a power switch and connector at the side.

The modular panel is neatly laid out. The PCIE and CPU power cables are coloured blue and the peripheral connectors are black. This ensures no installation problems can occur during the system build.

Above, an overview of the Corsair HX850 Professional Series Power Supply. It can deliver 70A (840 watts) to the single +12V rail. Ideal if you are using a pair of high end graphics cards in a Crossfire or SLI configuration.

Corsair are using a Ong Hua fan, a 14cm model (HA1425H12B-Z) with 7 blades. The fan is rated to spin at a maximum of 2,800 rpm. We have seen versions of this fan in several OCZ power supplies before.

The CWT design has been well put together and we immediately notice very few heatsinks inside the unit. The more efficient designs can make do with fewer heatsinks.

The Corsair custom CWT PCB is shared between the 750W, 850W and 1050W models. The company have clearly opted to use high grade components, selecting 105C rated Japanese capacitors on both primary and secondary stages. Corsair claim this power supply can deliver a continuous power delivery at a temperature rating of 50c.

The cables are sleeved and tied into the chassis with a protective plastic covering. This will ensure that no fraying can occur over the long term.

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
• Extech digital sound level meter
• 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
100W	1.54	3.35	1.77	5.04	6.65	12.11	0.50	5.03	0.20	-12.00
225W	3.74	3.33	3.84	5.02	15.59	12.08	1.00	5.01	0.20	-12.02
450W	7.53	3.32	8.32	5.00	30.78	12.04	1.50	5.00	0.30	-12.05
675W	11.32	3.30	12.31	4.98	47.48	12.01	2.00	4.99	0.50	-12.07
850W	1.49	3.27	1.15	4.97	63.52	11.97	0.50	4.97	0.20	-12.10

No concerns with the load regulation, holding well across all output stages.

Corsair HX850 Professional Series	Maximum Load
	911W

We managed to get the PSU to achieve 911W before it would shut down, delivering around 61W 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	11.98	0.2	-12.02	0.50	5.01
165W	15.0	3.28	18.0	4.98	2.0	12.10	0.2	-12.02	0.50	5.02

The Corsair HX850 handles the intensive Cross Load test without a problem. It was tasked with 60A on the +12V rail and it held at 11.98V. The other rails delivered good 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	5	5	15	5
225W	5	10	20	10
450W	10	10	25	10
675W	15	15	35	15
850W	15	20	45	20

Noise suppression results are excellent, peaking at 45mV on the +12V rail when under full load. The other rails fall between 15mV and 20mV across the full range of loads. Well within industry tolerance specifications.

Efficiency (%)
100W	83.87
225W	87.66
450W	91.77
675W	90.88
850W	88.21

Efficiency is excellent, peaking at almost 92% at 50% load. Efficiency falls down to just over 88% 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 Refridgerator
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	<28.0
675W	32.8
850W	35.4

The power supply is basically silent under most conditions – the fan only spins up under specific load demands. In the last 30% of ultimate power output the fan rises a little, hovering around 30-33dBa. In the last 100W of power output the fan rises noticeably. We recorded a maximum of 35.4 dBa at full load. Excellent results.

Temperature (c)
	Intake	Exhaust
100W	36	39
225W	38	45
450W	41	48
675W	43	50
850W	45	54

The large fan copes well with the temperatures inside the HX850 chassis, aided by the high efficiency of the unit. There are very few heatsinks inside the HX850, so this result is important.

Maximum load	Efficiency
911W	87.42

At 911w, the efficiency level measures 87.42%. Not a practical situation to be running 24/7, but worth noting.

The HX850 Professional Series Power Supply is unquestionably another strong offering from Corsair. The custom Channel Well Technology design has no noticeable weaknesses, combining a high level of efficiency with much desired, low noise levels.

Aesthetically the design will fit into a wide range of systems, inoffensive, yet professionally finished with deep black paint able to resist a moderate level of abuse under normal circumstances. The paint didn't scratch when we pressed the tip of a screwdriver gently down the side panels for instance. The finish also doesn't attract fingerprints unnecessarily, which is always a bonus.

Technically, the unit is well balanced. It almost delivered 92% efficiency at 50 percent load which is an excellent result. The high efficiency has meant that Corsair have been able to reduce the clutter of heatsinks inside, improving the air flow across the components underneath the large fan.

Noise suppression is excellent, with all output falling well within industry tolerance levels. +12V peaked at 45mV, +3.3V peaked at 15mV and +5V peaked at 20mV. Acoustic performance is very strong, with the fan only becoming noticeably active when the power demand exceeded 750W.

Power regulation is stable and the design handled the intensive cross loading test without any concerns. The modular design is very welcome, ensuring that cable routing will never be a concern, especially in a high performance media system build.

In real world terms we tested this power supply with a system comprising 16GB of 2,400mhz DDR3 memory, two AMD HD7970 graphics cards in Crossfire, and an overclocked Core i7 3960K with liquid cooling. We looped 3DMark 11 for hours, and played Max Payne 3 without a hiccup.

You can buy the Corsair HX850W Professional Gold from Overclockers, for £139.99 inc vat.

Pros:

• Excellent load regulation.
• high efficiency.
• good quality of finish.
• quiet.
• modular.
• 7 year warranty.

Cons:

• not cheap.

Kitguru says: Another excellent power supply from Corsair.

Become a Patron!