Corsair AX850 850W Power Supply Review

paulktreg - 2010-08-12 13:45:14 in Power Supplies
Category: Power Supplies
Reviewed by: paulktreg   
Reviewed on: September 22, 2010
Price: $199.99

Introduction:

Corsair has been producing high quality, high speed memory modules for mission-critical servers, high-end workstations and the PC enthusiasts market since 1994. Their memory, from the cost effective Value Select range to their flagship Dominator range, is renowned for its quality and performance. Corsair still concentrates their resources on producing high quality memory modules, but today also offer a range of products aimed at the PC enthusiast and mainstream market. The Corsair product catalog now includes solid state and USB drives, PC enclosures, cooling solutions and power supplies.

Corsair recently introduced three Professional Series Gold power supplies, the AX range, with DC output powers of 750 W, 850 W and 1200 W. They all carry 80 Plus Gold certification and come with a fully modular cabling system, making them Corsair's current flagship range. I recently put the AX1200 through its paces and it turned out to be one of the best units I have ever tested. This time it’s the turn of the AX850 so let’s have a close look and see how well this one performs.

 

Closer Look:

The Corsair AX850 packaging very closely follows the theme used by the AX1200, black and white with a splash of gold, with minor differences to reflect the changes in its specification. The top face of the box carries a photograph of the modular cable connector panel with a white Corsair logo in the top corner along with a short sentence or two with regards to its Professional Series Gold status and 850 W output power. The bottom face of the box carries the technical detail that includes photographs and quantities of connectors, fan noise and efficiency graphs, a specification table, and an outline of the main features in five different languages.

 

 

 

 

 

 

 

 

 

The side panels carry a few short paragraphs to emphasize the Corsair AX850 power supplies professional gold status along with a further set of features, again in five different languages.

 

 

Identical side panels include a photograph of the fan grill, model number, and the Corsair logo.

 

The AX1200 had a plain brown cardboard box within the box but it now comes with the addition of a large black Corsair logo on the top face.

 

Lift the lid and the instruction manual sits on top of the power supply foam protective cover with the accessories tucked neatly down the side. Top foam cover removed to show the black felt drawstring bag enclosed power supply.

 

 

The next pictures show the bagged power supply along with the box contents, which includes power cord, user manual, cable ties, mounting screws, and black modular cable bag.

 

 

The high quality packaging from Corsair is typical from a company like this.  Everything is included for a successful and tidy installation. There are no problems here, so onwards.

Closer Look:

The Corsair AX850 power supply is finished off with a coat of slightly textured satin black paint that is great for hiding finger prints and minor scratches.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The rear face of the power supply is home for the usual stuff: the IEC mains input connector, on/off switch, AX850 model number panel and an exhaust grill that occupies a large area to maximize cooling. The modular cable connector panel is on the front face along with a round holographic sticker that acknowledges Ultra Products as the patent holder for the fully modular power supply technology.

 

 

The side panels carry identical AX850 model labels bearing the black and white Corsair logo which is inverted on the opposite face.

 

The base of the Corsair AX850 carries a comprehensive specification label that includes a specification table, agency approval logos, and hazardous / high voltage warnings in several different languages. The cooling fan grill follows the black theme with a Corsair logo at its center.

 

 

The modular cable set is large, which is to be expected, and required two photographs to really show it off. The main cables, which include the motherboard, EPS12V/ATX12V, and PCI-E cables, are of the more traditional braided round design. The peripheral cables, which include 4-pin peripheral and SATA power, are constructed using Corsairs flat cable design to ease installation and cable management. The floppy disk drive is a rare animal these days but Corsair provide two 4-pin peripheral to FDD power connector adapters cables, should they be needed.

 

 

The construction of the power supply enclosure is slightly different from the norm in that the side panels are part of the main housing and the fan is mounted to the lid. Corsair has used the San Ace 120 (12cm) double ball bearing fan rated at 12 V/0.9 A and manufactured by Sanyo Denki. The printed circuit is very cramped but the layout is tidy. The first thing I noticed is a lack of large heavy heat sinks which is probably a reflection of its high efficiency leading to low levels of heat production. Wiring inside the Corsair AX850 has been kept to minimum to reduce voltage drops and increase efficiency.

 

 

The wiring has been dramatically reduced by mounting two DC-DC converters, one for the 3.3 V rail and another for 5 V rail, on the same printed circuit board as the modular cable connectors on the rear panel. The 12 V regulator is on the main base board and to help reduce loses a low current 12 V feed is taken to supply the 3.3 V and 5 V rails and a separate high current feed for the main 12 V rail. The capacitors are a mixture of conventional electrolytic by Nippon Chemi-Con and some solid state capacitors used mainly on the DC-DC converters.

 

 

The Corsair AX850 power supply build quality is excellent with the usual high quality packaging, good set of accessories, and comprehensive user manual. Let’s move on and have a look at the specification and features and then see how well it performs.

Specification:

 

Review Sample: Corsair 850AX 850W Power Supply, Part Number CMPSU-850AX.

 

Ratings Table:

 

 

 

 

 

 

 

 

 

 

 

 

Corsair AX850 850W (CMPSU-850AX) Power Supply Specification Table
AC Input
90-264V     10-5A     50-60Hz
DC Output
+3V3
+5V
+12V
-12V
+5VSB
Maximum Load
25A
25A
70A
0.5A
3A
Maximum Combined
Wattage
125W
840W
6W
15W
850W

 

System Protection:

"The Corsair Professional Series Gold AX850 power supply conforms to all required international safety standards, providing industrial grade protection. All outputs are monitored for over-current, under-voltage and over-voltage conditions. Over-Current Protection (OCP) is present on all rails, including the single +12V rail. Over-Temperature Protection (OTP) and Short-Circuit Protection (SCP) are both also included."

 

Safety & Agency Approvals:

 

Corsair AX850 850W (CMPSU-850AX) Power Supply Safety & Agency Approvals
FCC
FCC Rules Part 15, Class B
ICES
ICES-003
CE
EN 55022:2006+A1:2007 Class B, EN61000-3-2:2006 Class D, EN61000-3-3:1995+A1:2001 +A2:2005, EN55024:1998+A1:2001+A2:2003, IEC61000-4-2:1995+A1:1998+A2:2000, IEC61000-4-3:2006, IEC61000-4-4:2004, IEC61000-4-5:2005, IEC61000-4-6:2003+A1:2004+A2:2006, IEC61000-4-8:1993+A1:2000, IEC61000-4-11:2004
UL/CUL
UL60950-1
CSA
C22.2 NO. 60950-1
C-TICK
AS/NZS CISPR 22:2006 CLASS B
TUV
EN 60950-1
cTUVus
UL 60950-1:2007&CAN/CSA C22.2 NO. 60950-1
CB
IEC 60950-1
CCC
GB4943, GB9254, GB17625.1
BSMI
CNS14336, CNS13438
GOST
R IEC 60950-1-2005, R 51318.22-99, R 51318.24-99, R 51317.3.2-2006, R 51317.3.3-99
ROHS
2002/95/EC, Restrictions of Hazardous Substances Directive
WEEE
2002/96/EC, Waste Electrical and Electronic Equipment Directive
ROHS (China)
China Order No.39, Administration on the Control of Pollution Caused By Electronic Information Products

 

Power Supply Physical Characteristics:

 

Corsair AX850 850W (CMPSU-850AX) Power Supply Physical Characteristics
Weight
Length
Width
Height
4.2lbs/1.9kg
6.3in/160mm
5.9in/150mm
3.4in/87mm

 

Power Supply Connectors:

 

Corsair AX850 850W (CMPSU-850AX) Power Supply Connectors
Connector Type
Qty
Motherboard 20+4 Pin
1
ATX12V/EPS12V 4+4 Pin
2
PCI-E 6+2 Pin
4
SATA Power 15 Pin
12
Peripheral 4 Pin
8
FDD 4 Pin
2

 

Power Supply Cable Lengths:

Corsair AX850 850W (CMPSU-850AX) Power Supply Cable Set
Cable Type
Cable Length/Connector Spacing’s
Qty
Modular
PSU > 24" > Motherboard 20+4 Pin
1
Modular
PSU > 24" > ATX12V/EPS12V 4+4 Pin
2
Modular
PSU > 24" > 2 x PCI-E 6+2 Pin
2
Modular
PSU > 16" > SATA > 6" > SATA > 6" > SATA > 6" > SATA
2
Modular
PSU > 16" > SATA > 6" > SATA
2
Modular
PSU > 16" > Peripheral > 6" > Peripheral > 6" > Peripheral > 6" > Peripheral
2
Adapter
Peripheral > 4" > FDD
2

 

Features:

Unprecedented power protection:

The Corsair Professional Series Gold power supply pushes the state of the art for reliable delivery of clean power under imperfect conditions. If you require mission-critical stability or you simply want one of the best power supplies available, the Professional Gold is for you.

 

A true modular cable system:

All cables detach from the power supply. During installation, this gives you the flexibility of using only cables that you need for a clean system build with optimal airflow. And, when its time to replace or upgrade your power supply, it can be removed from your system without interfering with your cabling - the cables stay in place and connect to your new fully-modular Corsair power supply.

 

Incredible efficiency:

With 90% efficiency at 50% load, the Cosair Professionl Series Gold power supply runs quieter, generates minimal excess heat, and saves you money every month. It's earned the 80 Plus Gold seal of approval, your guarantee that you're making the right choice for smart, efficient power delivery.

 

Testing:

For more information on how we test our power supplies, please browse our testing methodology.

Electrical Safety:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Electrical Safety Test Class 1
Manufacturer/Model
Pass/Fail
Corsair AX850
Pass

 

Short Circuit Protection:

I short circuited the 3V3, 5V0, and the 12V in turn. The power supply did shut down, and once the short was removed and the unit switched off for at least one second, resumed normal operation. Although listed here at the beginning of the testing section, I tend to leave this test until the very end, in case it doesn't quite go to plan.

 

DC Output Voltage Load Regulation:

 

Mains Input Voltage 110VAC

 

 

Corsair AX850 850W (CMPSU-850AX) DC Output Voltage Load Regulation
Supply = 110VAC/50Hz
PSU DC Rail
Measured Voltage(V)
3V3
3.39
5V0
5.04
+12V
12.23
-12V
11.88
5VSB
5.11
Total PSU DC Loading = 0W (0% of Rated Maximum Output Power)

 

Corsair AX850 850W (CMPSU-850AX) DC Output Voltage Load Regulation
Supply = 110VAC/50Hz
PSU
DC Rail
Rail Loading Amps (A)
Rail Loading Watts (W)
Measured Voltage (V)
ATX12V V2.2 Limits (V)
Pass/Fail
+3V3
3.17
10.68
3.37
3.135 – 3.465
Pass
+5V
4.70
23.64
5.03
4.75 – 5.25
Pass
+12V
10.20
124.44
12.20
11.4 – 12.6
Pass
-12V
0.35
4.15
11.85
10.8 – 13.2
Pass
+5VSB
2.12
10.45
4.93
4.75 – 5.25
Pass
Total PSU DC Loading = 173W (19% of Rated Maximum Output Power)

 

Corsair AX850 850W (CMPSU-850AX) DC Output Voltage Load Regulation
Supply = 110VAC/50Hz
PSU
DC Rail
Rail Loading Amps (A)
Rail Loading Watts (W)
Measured Voltage (V)
ATX12V V2.2 Limits (V)
Pass/Fail
+3V3
3.16
10.68
3.38
3.135 – 3.465
Pass
+5V
4.66
23.35
5.01
4.75 – 5.25
Pass
+12V
31.76
387.47
12.20
11.4 – 12.6
Pass
-12V
0.35
4.15
11.87
10.8 – 13.2
Pass
+5VSB
2.11
10.29
4.88
4.75 – 5.25
Pass
Total PSU DC Loading = 436W (51% of Rated Maximum Output Power)

 

Corsair AX850 850W (CMPSU-850AX) DC Output Voltage Load Regulation
Supply = 110VAC/50Hz
PSU
DC Rail
Rail Loading Amps (A)
Rail Loading Watts (W)
Measured Voltage (V)
ATX12V V2.2 Limits (V)
Pass/Fail
+3V3
7.94
26.52
3.34
3.135 – 3.465
Pass
+5V
9.19
45.77
4.98
4.75 – 5.25
Pass
+12V
62.64
759.20
12.12
11.4 – 12.6
Pass
-12V
0.35
4.17
11.92
10.8 – 13.2
Pass
+5VSB
2.04
9.77
4.79
4.75 – 5.25
Pass
Total PSU DC Loading = 845W (100% of Rated Maximum Output Power)

 

Mains Input Voltage 230VAC

 

 

Corsair AX850 850W (CMPSU-850AX) DC Output Voltage Load Regulation
Supply = 230VAC/50Hz
PSU DC Rail
Measured Voltage(V)
3V3
3.40
5V0
5.04
+12V
12.23
-12V
11.88
5VSB
5.10
Total PSU DC Loading = 0W (0% of Rated Maximum Output Power)

 

Corsair AX850 850W (CMPSU-850AX) DC Output Voltage Load Regulation
Supply = 230VAC/50Hz
PSU
DC Rail
Rail Loading Amps (A)
Rail Loading Watts (W)
Measured Voltage (V)
ATX12V V2.2 Limits (V)
Pass/Fail
+3V3
3.18
10.72
3.37
3.135 – 3.465
Pass
+5V
4.69
23.54
5.02
4.75 – 5.25
Pass
+12V
10.23
124.80
12.20
11.4 – 12.6
Pass
-12V
0.35
4.15
11.87
10.8 – 13.2
Pass
+5VSB
2.12
10.47
4.94
4.75 – 5.25
Pass
Total PSU DC Loading = 174W (20% of Rated Maximum Output Power)

 

Corsair AX850 850W (CMPSU-850AX) DC Output Voltage Load Regulation
Supply = 230VAC/50Hz
PSU
DC Rail
Rail Loading Amps (A)
Rail Loading Watts (W)
Measured Voltage (V)
ATX12V V2.2 Limits (V)
Pass/Fail
+3V3
3.18
10.75
3.38
3.135 – 3.465
Pass
+5V
4.70
23.59
5.02
4.75 – 5.25
Pass
+12V
31.71
386.86
12.20
11.4 – 12.6
Pass
-12V
0.35
4.15
11.87
10.8 – 13.2
Pass
+5VSB
2.11
10.34
4.90
4.75 – 5.25
Pass
Total PSU DC Loading = 436W (51% of Rated Maximum Output Power)

 

Corsair AX850 850W (CMPSU-850AX) DC Output Voltage Load Regulation
Supply = 230VAC/50Hz
PSU
DC Rail
Rail Loading Amps (A)
Rail Loading Watts (W)
Measured Voltage (V)
ATX12V V2.2 Limits (V)
Pass/Fail
+3V3
7.95
26.55
3.34
3.135 – 3.465
Pass
+5V
9.22
45.92
4.98
4.75 – 5.25
Pass
+12V
62.68
759.68
12.12
11.4 – 12.6
Pass
-12V
0.35
4.17
11.92
10.8 – 13.2
Pass
+5VSB
2.04
9.91
4.86
4.75 – 5.25
Pass
Total PSU DC Loading = 846W (100% of Rated Maximum Output Power)

 

The Corsair AX850 produced a great set of results in this section with all the rails holding steady from zero to full load. Again, there aren't any problems here so let's move on.

Testing:

Efficiency and Power Factor:

 

 

 

 

 

 

 

 

 

 

 

 

 

Testing for 80 Plus certification is almost always performed with the mains supply at 115 VAC nominal and 60 Hz no doubt to cater for the North American market. The requirements for Gold certification are 87%, 90%, 87% efficiency at 20%, 50%, 100% DC load with a power factor of >0.9 at 50% DC loading. The graphs above show the power factor levels are fine but the efficiency levels for 80 Plus Gold aren’t reached following the OCC testing methodology with the dip to 83% at full load a little unexpected.

 

 

The efficiency levels although not quite hitting 80 Plus Gold are better at 230 Vac but then this is usually the case and a maximum efficiency of 89%, following the OCC testing methodology, is still up there with other high end units.

It would be unfair to “fail” the power supply based on the OCC testing methodology because I can’t maintain the AC mains supply at exactly 115 V throughout testing and my rail loadings aren’t in line with the protocols laid down by the test specification. A great if not exceptional set of results in this section still make the Corsair AX850 one of the more efficient power supplies available at the present time.

 

 

AC Ripple On DC Outputs:

I have consistently found the AC ripple levels on the DC rails to be more or less equal with a 110VAC or 230VAC mains supply. The results given below are for 230VAC only but I will continue to check the levels at 110VAC during testing and publish them below if there are any significant differences.

 

AC ripple/noise on the +3V3 rail at 230VAC

Oscilloscope settings: Amplitude = 5mV/div, Timebase = 20uS/div

 

AC ripple/noise on the +5V0 rail at 230VAC

Oscilloscope settings: Amplitude = 5mV/div, Timebase = 20uS/div

 

AC ripple/noise on the +12V rail at 230VAC

Oscilloscope settings: Amplitude = 5mV/div, Timebase = 20uS/div

 

AC ripple/noise on the -12V rail at 230VAC

Oscilloscope settings: Amplitude = 5mV/div, Timebase = 20uS/div

 

AC ripple/noise on the +5VSB rail at 230VAC

Oscilloscope settings: Amplitude = 5mV/div, Timebase = 20uS/div

 

Corsair AX850 850W (CMPSU-850AX) AC Ripple/Noise
Supply = 230VAC/50Hz DC Loading = 846W
DC Rail
+3V3
+5V0
+12V
-12V0
+5VSB
ATX12 Max (mV p-p)
50
50
120
120
50
Measured Ripple (mV p-p)
16
28
22
36
27
Pass/Fail
Pass
Pass
Pass
Pass
Pass

The Corsair AX850 power supply produced a low set of results for AC ripple/noise on all the rails and remained well within the levels set down by the ATX12V specification.

Testing(Continued):

Temperature, Noise Levels and Fan Speeds:

I am not going to give a pass or fail in this section, as the ATX12V V2.2 does not really have any references on which to base a decision.

Temperatures are purely for information only, as there are too many variables involved when installed in a case, which, by the way, it wasn't. Ambient temperature, processor cooling efficiency, and case cooling fans all play their part on the temperature of the air entering the power supply, and consequently the temperature of the air leaving it. No valid conclusions can be made from this test.

 

 

 

 

 

 

 

 

 

 

 

 

 

Corsair AX850 850W (CMPSU-850AX) Temperature & Fan Speeds
Supply = 110/230VAC
DC Loading(W)
Temp In (°C)
Temp Out (°C)
Δ Temp (°C)
Fan Speed (RPM)
0
N/A
N/A
N/A
0/0
173/174
N/A
N/A
N/A
0/0
436/436
23.2/23.0
31.5/29.5
8.3/6.5
543/542
845/846
24.1/24.1
32.2/30.9
8.1/6.8
1957/1945

 

The Corsair AX850 employs silent fan control technology that explains the zero fan speed at no load and 170 W loading. The graph below explains it in a little more detail.

 

I have indicated zero fan speed at 170 W which isn’t strictly speaking true because the fan kicked in very intermittently at this level at 300 rpm for few seconds. The silent fan control technology means, according to the graph, no fan noise up to approximately 150W because it won’t be spinning and virtually no fan noise up to 425W at only 10 dBA, a very welcome feature for most enthusiasts I’m sure. The fan noise does ramp up beyond 425W and at full load it becomes noticeably louder but no more than other power supplies in this class. Temperatures remained very low at all times, but once again, please are aware that it wasn’t installed in a case and no hot boxes have been used.

Conclusion:

 

Price Per the Watt:

Power Supply Corsair AX850 850W at $199.99 = $0.23/Watt (08-2010)

 

The Corsair AX850 performed very well during testing.  However, following the OCC testing methodology, the efficiency figures were a little disappointing, especially on 110 VAC at full load. It is certified by the 80 Plus organization to meet the requirements of the Gold standard; if I could replicate the results at the same DC loading and AC input then maybe it would meet the said standard, but it would be unfair to downgrade the power supply in any way because the power supply will be optimized by Corsair to meet the standard at particular AC input and DC loading levels. DC voltage load regulation and AC ripple/noise are excellent, which really are the most important factors when on the hunt for a suitable power supply for benching and high end gaming rigs. Don’t get me wrong, I’m all for saving precious resources and an 80 Plus certified power supply should be a must; it assures a certain level of quality in itself.

What I really like about the Corsair AX850 is the silent fan control technology and the results it produces. Let’s face it, you’re not going to get silence when used in an high end dual graphics card set up playing a round of Crysis and it wouldn’t really benefit me because I usually fold when not gaming and the loudest thing I hear is my graphics card fan, a quiet power supply really wouldn’t make much difference. It will benefit the gamer that likes a silent PC while at the desktop, surfing, or using productivity software and enjoys quiet while gaming on a single high end graphics card.

The Corsair AX850 performed very well during testing but it didn’t quite hit the efficiency marks expected following the OCC testing methodology, but 89% isn’t too bad, is it? It comes highly recommended and I have no hesitation in awarding it an OCC Gold award.

 

Pros:

 

Cons: