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Even though the original Corsair HX850 power supply received the 80 Plus Gold certification, Corsair decided to downgrade it to the 80 Plus Silver certification, as the manufacturer felt the 80 Plus Gold levels couldn’t be sustained at high temperatures. (Wouldn’t it be great if all manufacturers had this kind of concern?) Now Corsair is releasing a revamped version of its HX850, the HX850 Gold. Let’s see if this new version is a good product.
Officially, the name of the new version of the HX850 is simply “HX850.” We decided to call it “HX850 Gold” to make it clear which product we are talking about, since Corsair didn’t opt to include a “V2” after the name of this new unit, as it has been doing with the revised version of its other power supplies. The original HX850 used the part number “CMPSU-850HX,” but the new model has a completely different part number: “CP-9020032.”
Similarly to the original HX850, the HX850 Gold is manufactured by CWT. Internally, however, the two units are completely different.
The Corsair HX850 Gold is 7.1” (180 mm) deep, using a 140 mm ball-bearing fan on its bottom (Hong Hua HA1425H12B-Z). The power supply only turns on its fan when load is above 20 percent. This way, the power supply produces no noise at light loads.
The reviewed power supply has a modular cabling system with 10 connectors: four for video cards or ATX12V/EPS12V connectors and six for SATA or peripheral power connectors. The main motherboard cable, the ATX12V/EPS12V cable, and two video card cables are permanently attached to the power supply. These cables are protected with nylon sleeves, which come from inside the unit. This power supply comes with the following cables:
- Main motherboard cable with a 20/24-pin connector, 22” (56 cm) long, permanently attached to the power supply
- One cable with two ATX12V connectors that together form an EPS12V connector, 25.2” (64 cm) long, permanently attached to the power supply
- One cable with two ATX12V connectors that together form an EPS12V connector, 22” (56 cm) long, modular cabling system
- Two cables, each with one six/eight-pin connector for video cards, 22” (56 cm) long, permanently attached to the power supply
- Four cables, each with one six/eight-pin connector for video cards, 22” (56 cm) long, modular cabling system
- Three cables, each with four SATA power connectors: one cable with 21.6” (55 cm) to the first connector and 3.9” (10 cm) between connectors, and two cables with 15.8” (40 cm) to the first connector and 3.9” (10 cm) between connectors, modular cabling system
- Three cables, each with four standard peripheral power connectors, 17.7” (45 cm) to the first connector, 3.9” (10 cm) between connectors, modular cabling system
- Two adapters to convert one standard peripheral power connector into one floppy disk drive power connector
All wires are 18 AWG, which is the minimum recommended gauge, except the main motherboard cable, which uses thicker 16 AWG wires. The number of connectors is excellent for an 850 W power supply, allowing you to install three high-end video cards that require two auxiliary power connectors each without the need for adapters.
Let’s now take an in-depth look inside this power supply.
[nextpage title=”A Look Inside the Corsair HX850 Gold”]
We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our “Anatomy of Switching Power Supplies” tutorial to understand how a power supply works and to compare this power supply to others.
On this page we will have an overall look, and then in the following pages we will discuss in detail the quality and ratings of the components used.
[nextpage title=”Transient Filtering Stage”]
As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil.
In the transient filtering stage, this power supply is flawless, with two Y capacitors and one X capacitor more than the minimum required.
On the next page, we will have a more detailed discussion about the components used in the Corsair HX850 Gold.
[nextpage title=”Primary Analysis”]
On this page we will take an in-depth look at the primary stage of the Corsair HX850 Gold. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
This power supply uses two GBU1006 rectifying bridges connected in parallel and attached to an individual heatsink. Each bridge supports up to 10 A at 100° C. So, in theory, you would be able to pull up to 2,300 W from a 115 V power grid. Assuming 80% efficiency, these bridges would allow this unit to deliver up to 1,840 W without burning themselves out (up to 3,105 W at 90% efficiency). Of course, we are only talking about these particular components. The real limit will depend on all the components combined in this power supply.
The active PFC circuit uses two IPW60R099C6 MOSFETs, each supporting up to 37.9 A at 25° C or 24 A at 100° C in continuous mode (see the difference temperature makes) or 112 A at 25° C in pulse mode. These transistors present a maximum 99 mΩ resistance when turned on, a characteristic called RDS(on). The lower the number the better, meaning that the transistor will waste less power, and the power supply will have a higher efficiency.
The output of the active PFC circuit is filtered by two 390 µF x 420 V Japanese electrolytic capacitors, from Chemi-Con, labeled at 105° C. These capacitors are connected in parallel and are the equivalent of a single 780 µF x 420 V capacitor.
In the switching section, another two IPW60R099C6 MOSFETs are employed using the traditional two-transistor forward configuration. The specifications for these transistors were already discussed above.
The switching transistors are managed by a CM6802 active PFC/PWM combo controller.
Let’s now take a look at the secondary of this power supply.
[nextpage title=”Secondary Analysis”]
The Corsair HX850 Gold uses a synchronous design, meaning that the rectifiers were replaced with MOSFETs. Also, this power supply uses a DC-DC design, meaning that it is basically a +12 V power supply, with the +5 V and +3.3 V outputs being generated through two smaller switching power supplies connected to the +12 V rail. Both designs are used to increase efficiency.
The +12 V output uses six transistors: three IPD031N06L3 G MOSFETs, each supporting up to 100 A at 100° C in continuous mode or up to 400 A at 25° C in pulse mode, with a maximum RDS(on) of 3.1 mΩ; and three CEB6056 MOSFETS, each supporting up to 100 A at 25° C in continuous mode or up to 360 A at 25° C in pulse mode, with a maximum RDS(on) of 6.2 mΩ. These transistors are controlled by an SP6019 integrated circuit, and they are located on a small daughterboard.
The DC-DC converters are located on the same printed circuit board as the modular cabling system. Both are managed by an APW7159 PWM controller, with each output using four AP72T03GH MOSFETs, each supporting up to 63 A at 25° C or 44 A at 100° C in continuous mode or up to 190 A at 25° C in pulse mode, with a maximum RDS(on) of 9 mΩ.
The outputs of this power supply are monitored by a WT7502 integrated circuit, which only supports over voltage (OVP) and under voltage (UVP) protections.
This power supply uses a mix of Japanese electrolytic capacitors, from Chemi-Con, and solid capacitors to filter its outputs. See Figure 20.
[nextpage title=”Power Distribution”]
In Figure 21, you can see the power supply label containing all the power specs.
As you can see, this power supply has a single +12 V rail, so there is not much to talk about here.
How much power can this unit really deliver? Let’s find out.
[nextpage title=”Load Tests”]
We conducted several tests with this power supply, as described in the article, “Hardware Secrets Power Supply Test Methodology.”
First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching the behavior of the reviewed unit under each load. In the table below, we list the load patterns we used and the results for each load.
If you add all the powers listed for each test, you may find a different value than what is posted under “Total” below. Since each output can have a slight variation (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. In the “Total” row, we are using the real amount of power being delivered, as measured by our load tester.
The +12VA and +12VB inputs listed below are the two +12 V independent inputs from our load tester. During this test, both inputs were connected to the power supply’s single +12 V rail. (The power supply’s EPS12V connector was installed on the +12VB input of the load tester.)
|Input||Test 1||Test 2||Test 3||Test 4||Test 5|
|+12VA||6 A (72 W)||13 A (156 W)||19 A (228 W)||25.5 A (306 W)||32 A (384 W)|
|+12VB||6 A (72 W)||13 A (156 W)||19 A (228 W)||25.5 A (306 W)||31.5 A (378 W)|
|+5 V||1 A (5 W)||2 A (10 W)||4 A (20 W)||6 A (30 W)||8 A (40 W)|
|+3.3 V||1 A (3.3 W)||2 A (6.6 W)||4 A (13.2 W)||6 A (19.8 W)||8 A (26.4 W)|
|+5VSB||1 A (5 W)||1.5 A (7.5 W)||2 A (10 W)||2.5 A (12.5 W)||3 A (15 W)|
|-12 V||0.5 A (6 W)||0.5 A (6 W)||0.5 A (6 W)||0.5 A (6 W)||0.5 A (6 W)|
|Total||163.8 W||342.4 W||503.5 W||675.2 W||848.4 W|
|% Max Load||19.3%||40.3%||59.2%||79.4%||99.8%|
|Room Temp.||45.4° C||44.9° C||46.2° C||47.6° C||49.4° C|
|PSU Temp.||42.2° C||43.2° C||44.2° C||45.6° C||48.7° C|
|Ripple and Noise||Pass||Pass||Pass||Pass||Pass|
|AC Power||183.8 W||377.2 W||560.2 W||764.0 W||980.0 W|
|AC Voltage||116.1 V||114.1 V||111.7 V||110.0 V||106.6 V|
The 80 Plus Gold certification promises a minimum efficiency of 90% at typical load (i.e., 50% load) and a minimum efficiency of 87% at light (i.e., 20% load) and full loads. The Corsair HX850 Gold presented efficiency between 86.6% and 90.8% during our tests. At the full load test, efficiency was a tad below 87%, which can be explained by the AC voltage at our lab that dropped to 106.6 V, and power supplies present lower efficiency at lower AC voltages. Therefore, we can claim the Corsair HX850 Gold passed our efficiency tests.
All positive voltages were closer to their nominal values during all tests (3% voltage regulation). The -12 V output was outside this tighter range during tests one (at -11.41 V), two (at -11.48 V), and three (-11.55 V), but still inside the allowed range. The ATX12V specification states that positive voltages must be within 5% of their nominal values, and negative voltages must be within 10% of their nominal values.
Let’s discuss the ripple and noise levels on the next page.
[nextpage title=”Ripple and Noise Tests”]
Voltages at the power supply outputs must be as “clean” as possible, with no noise or oscillation (also known as “ripple”). The maximum ripple and noise levels allowed are 120 mV for +12 V and -12 V outputs, and 50 mV for +5 V, +3.3 V and +5VSB outputs. All values are peak-to-peak figures. We consider a power supply as being top-notch if it can produce half or less of the maximum allowed ripple and noise levels.
The Corsair HX850 Gold provided extremely low ripple and noise levels, making it a “flawless” unit here.
|Input||Test 1||Test 2||Test 3||Test 4||Test 5|
|+12VA||12.4 mV||14.0 mV||16.6 mV||20.4 mV||25.6 mV|
|+12VB||10.4 mV||12.6 mV||15.2 mV||19.4 mV||23.8 mV|
|+5 V||9.8 mV||9.6 mV||9.8 mV||10.4 mV||10.4 mV|
|+3.3 V||8.2 mV||10.0 mV||12.6 mV||14.2 mV||13.6 mV|
|+5VSB||7.8 mV||9.8 mV||12.6 mV||14.4 mV||17.8 mV|
|-12 V||35.0 mV||41.0 mV||51.2 mV||61.4 mV||73.4 mV|
Below you can see the waveforms of the outputs during test five.
[nextpage title=”Overload Tests”]
Below you can see the maximum we could pull from this power supply. The objective of this test is to see if the power supply has its protecti
on circuits working properly. This unit passed this test, as it shut down when we tried to pull more than what is listed in the table below. Noise and ripple levels were still extremely low, but the +3.3 V output dropped to +3.13 V, the +5 V output dropped to +4.84 V, and the +5VSB output dropped to +4.84 V as well.
|+12VA||33 A (396 W)|
|+12VB||33 A (396 W)|
|+5 V||22 A (110 W)|
|+3.3 V||22 A (72.6 W)|
|+5VSB||3 A (15 W)|
|-12 V||0.5 A (6 W)|
|% Max Load||116.6%|
|Room Temp.||46.6° C|
|PSU Temp.||48.4° C|
|AC Power||1,212 W|
|AC Voltage||101.6 V|
[nextpage title=”Main Specifications”]
The main specifications for the Corsair HX850 Gold power supply include:
- Standards: ATX12V 2.31 and EPS12V 2.91
- Nominal labeled power: 850 W at 50° C
- Measured maximum power: 991.4 W at 46.6° C
- Labeled efficiency: 80 Plus Gold certification
- Measured efficiency: Between 86.6% and 90.8%, at 115 V (nominal, see complete results for actual voltage)
- Active PFC: Yes
- Modular Cabling System: Yes
- Motherboard Power Connectors: One 20/24-pin connector and two ATX12V connectors that together form an EPS12V connector permanently attached to the power supply and two ATX12V connectors that together form an EPS12V connector on the modular cabling system
- Video Card Power Connectors: Six six/eight-pin connectors on separate cables, two permanently attached to the power supply and four on the modular cabling system
- SATA Power Connectors: 12 on three cables, modular cabling system
- Peripheral Power Connectors: 12 on three cables, modular cabling system
- Floppy Disk Drive Power Connectors: Two (converted from two peripheral power connectors)
- Protections (as listed by the manufacturer): NA
- Are the above protections really available? This unit has over voltage (OVP), under voltage (UVP), over power (OPP), and short-circuit (SCP) protections.
- Warranty: Seven years
- Real Manufacturer: CWT
- More Information: https://www.corsair.com
- MSRP in the U.S.: USD 200.00
The new Corsair HX850 Gold performed slightly better on our tests than the original HX850. Efficiency was higher at full load (at other loads it remained about the same), but the biggest advantage of the new version is that we didn’t see the high noise level on the +5VSB output that we saw with the original HX850. While noise levels with the original HX850 were very low, with the new HX850 Gold they were even lower. Voltage regulation was the same, with all positive voltages within 3% of their nominal values, i.e., closer to their nominal values than required by the ATX12V specification.
Another highlight of this power supply is its cable configuration, which allows you to install three high-end video cards that require two auxiliary power connectors each out of the box.
The suggested price for this unit is USD 200, and we know vendors sell power supplies for less than the suggested price. For example, the Corsair AX850, which is an 80 Plus Gold-certified unit with a full modular cabling system, has an MSRP of USD 230, but it is sold for USD 190 at Newegg.com. Therefore, it is fair to assume that the Corsair HX850 Gold will have a price tag of USD 180 or below, making it a very good buy for its performance and features, as well as being less expensive than its main competitor, the Seasonic X-Series 850 W.