[nextpage title=”Introduction”]
XFX recently released a new series of power supplies with the 80 Plus Gold certification and a fully modular cabling system, with 750 W, 850 W, 1,050 W, and 1,250 W versions, dubbed the PRO Black Edition Full Modular. Be aware that the name “PRO Black Edition” has already been used by XFX for an 80 Plus Bronze power supply series, and the new series has the “Full Modular” words added to its name. (The new models have the letters “BEF” added at the end of their part numbers.) Wouldn’t it be simpler to just use a different name? Anyway, we’ve already reviewed the 750 W model, which proved to be an outstanding unit. Let’s see if the 850 W version also deserves our recommendation.
The new XFX PRO Black Edition Full Modular series power supplies are rebranded Seasonic X-Series KM3 units. The latest models within Corsair’s AX series are also based on the same platform.
Figure 1: XFX PRO 850 W Black Edition Full Modular power supply
Figure 2: XFX PRO 850 W Black Edition Full Modular power supply
The XFX PRO 850 W Black Edition Full Modular is 6.3” (160 mm) deep. It uses a 120 mm ball-bearing fan on its bottom (ADDA AD1212MB-A70GL; models from Seasonic and Corsair based on the same platform use a fan from Sanyo Denki). The power supply has a “hybrid/normal” switch that allows you to configure the fan to turn on only when the power supply load reaches 30% of the unit’s labeled wattage (i.e., 255 W), so the power supply won’t make any noise when the computer doesn’t demand a lot of power. Under the “hybrid” mode, between 30% and 50% load, the fan will spin at a lower speed, generating lower noise than usual.
Figure 3: Fan
The modular cabling system from this power supply has 13 connectors: two for the main motherboard power connector, six for video card and ATX12V/EPS12V connectors, and five for peripheral and SATA connectors. This power supply comes with the following cables:
- Main motherboard cable with a 20/24-pin connector, 23.6” (60 cm) long
- One cable with two ATX12V connectors that together form an EPS12V connector, 25.2” (64 cm) long
- One cable with one EPS12V connector, 25.2” (64 cm) long
- Two cables, each with two six/eight-pin connectors for video cards, 22” (56 cm) to the first connector, 3.9” (10 cm) between connectors
- Two cables, each with four SATA power connectors, 15.7” (40 cm) to the first connector, 4.7” (12 cm) between connectors
- One cable with two SATA power connectors, 12.6” (32 cm) to the first connector, 4.7” (12 cm) between connectors
- One cable with three peripheral power connectors, 15.7” (40 cm) to the first connector, 4.7” (12 cm) between connectors
- One cable with two peripheral power connectors, 12.6” (32 cm) to the first connector, 4.7” (12 cm) between connectors
- Two adapters to convert a standard peripheral power connector into a floppy disk drive power connector
All wires are 18 AWG, which is the minimum recommended gauge.
This is the same configuration used by the 750 W model, allowing you to install up to two high-end video cards that require two auxiliary power connectors each. We think XFX could have added a third video card cable in order to support out-of-the-box installation of three high-end video cards.
Figure 4: Cables
Let’s now take an in-depth look inside this power supply.
[nextpage title=”A Look Inside the XFX PRO 850 W Black Edition Full Modular”]
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.
Figure 5: Top view
Figure 6: Front quarter view
Figure 7: Rear quarter view
Figure 8: The printed circuit board
[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.
Figure 9: Transient filtering stage (part 1)
Figure 10: Transient filtering stage (part 2)
On the next page, we will have a more detailed discussion of the components used in the XFX PRO 850 W Black Edition Full Modular.[nextpage title=”Primary Analysis”]
On this page, we will take an in-depth look at the primary stage of the XFX PRO 850 W Black Edition Full Modular. For a better understanding, please read our “Anatomy of Switching Power Supplies” tutorial.
This power supply uses two GBJ1506 rectifying bridges, which are attached to an individual heatsink. Each bridge supports up to 15 A at 100° C. In theory, you would be able to pull up to 3,450 W from a 115 V power grid. Assuming 80% efficiency, the bridges would allow this unit to deliver up to 2,760 W without burning themselves out (or 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. These are the same components used on the 750 W version, the Seasonic X-Series KM3 650 W, and the Corsair AX760.
Figure 11: Rectifying bridges
The active PFC circuit uses two IPP60R199CP MOSFETs, each one supporting up to 16 A at 25° C or 10 A at 100° C in continuous mode (note the difference temperature makes), or 51 A at 25° C in pulse mode. These transistors present a 199 mΩ maximum 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. These transistors are “stronger” than the ones used in the 750 W model.
Figure 12: The active PFC diode and transistors
The active PFC circuit is controlled by an NCP1654 integrated circuit.
Figure 13: Active PFC controller
The output of the active PFC circuit is filtered by two 330 μF x 420 V Japanese electrolytic capacitors, from Hitachi, labeled at 105° C. These capacitors are connected in parallel and are the equivalent of a single 660 μF x 420 V capacitor. The 750 W model uses capacitors with lower capacitance here.
Figure 14: Capacitors
In the switching section, four IPP50R399CP MOSFETs are employed using a full-bridge, resonant configuration. Each transistor supports up to 9 A at 25° C or 6 A at 100° C in continuous mode or up to 20 A at 25° C in pulse mode, with a maximum RDS(on) of 399 mΩ. These are the same transistors used in the 750 W model and in the Seasonic X-Series KM3 650 W. The Corsair AX760 uses more powerful transistors here.
Figure 15: The switching transistors
The switching transistors are controlled by a CM6901 resonant controller, which is physically located on the same printed circuit board as the +12 V transistors.
Figure 16: Resonant controller
Let’s now take a look at the secondary of this power supply.
[nextpage title=”Secondary Analysis”]
As one would expect in a high-efficiency power supply, the XFX PRO 850 W Black Edition Full Modular uses a synchronous design, where the Schottky rectifiers are replaced with MOSFETs. Also, the reviewed product uses a DC-DC design in its secondary. This means that the power supply is basically a +12 V unit, with the +5 V and +3.3 V outputs produced by two smaller power supplies connected to the main +12 V rail. Both designs are used to increase efficiency.
The +12 V output uses four PSMN2R6-40YS MOSFETs, each one supporting up to 100 A at 100° C in continuous mode, or up to 651 A at 25° C in pulse mode, with a maximum RDS(on) of 3.7 mΩ. This is the same configuration used in the 750 W version of this power supply and in the Corsair AX760. The Seasonic X-Series KM3 650 W uses only two of these transistors.
Figure 17: The +12 V transistors
As explained, the +5 V and +3.3 V outputs are produced by two DC-DC converters, which are located on the same printed circuit board as the modular cabling system. The two converters are controlled by the same PWM controller, an APW7159, and each output makes use of three BSC0906NS MOSFETs, each one supporting up to 63 A at 25° C or 50 A at 100° C in continuous mode and up to 252 A at 25° C in pulse mode, with a maximum RDS(on) of 4.5 mΩ. This is exactly the same configuration used in the XFX’s 750 W version, in the Corsair AX760, and in the Seasonic X-Series KM3 650 W.
Figure 18: The DC-DC converters
Figure 19: The DC-DC converters
The outputs of the power supply are monitored by a WT7527 integrated circuit, which supports over voltage (OVP), under voltage (UVP), and over current (OCP) protections. There are four OCP channels, one for +3.3 V, one for +5 V, and two for +12 V. The manufacturer, however, decided to use only one of the +12 V channels available, resulting in this unit having a single +12 V rail.
Figure 20: Monitoring circuit
This power supply uses a mix of solid and electrolytic capacitors in its secondary. The electrolytic capacitors are also Japanese, from Chemi-Con, and labeled at 105° C, as usual.
Figure 21: Capacitors
[nextpage title=”The +5VSB Power Supply”]
The +5VSB (a.k.a. standby) power supply is independent of the main power supply, since it is on continuously.
The +5VSB power supply uses an ICE2QR4765 integrated circuit, which incorporates the PWM controller and the switching transistor into a single chip.
Figure 22: The +5VSB integrated circuit with an integrated switching transistor
The rectification of the +5VSB output is performed by an SBR30A40CT Schottky rectifier, which supports up to 30 A (15 A per internal diode at 110° C, 0.50 V maximum voltage drop).
Figure 23: The +5VSB rectifier
The +5VSB power supply of the XFX PRO 850 W Black Edition Full Modular is identical to the one used on the 750 W version of this same power supply.
[nextpage title=”Power Distribution”]
In Figure 24, you can see the power supply label containing all the power specs.
Figure 24: Power supply label
As you can see, this unit has a single +12 V rail configuration.
Let’s find out how much power this unit can deliver.
[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, the +12VA and +12VB inputs were connected to the power supply’s single +12 V rail. (The +12VB input was connected to the power supply EPS12V connector.)
| 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 | 164.4 W | 344.1 W | 506.8 W | 680.8 W | 846.7 W |
| % Max Load | 19.3% | 40.5% | 59.6% | 80.1% | 99.6% |
| Room Temp. | 45.3° C | 45.3° C | 46.8° C | 49.5° C | 46.0° C |
| PSU Temp. | 51.4° C | 51.6° C | 52.4° C | 54.7° C | 52.6° C |
| Voltage Regulation | Pass | Pass | Pass | Pass | Pass |
| Ripple and Noise | Pass | Pass | Pass | Pass | Pass |
| AC Power | 181.2 W | 376.9 W | 559.8 W | 765.0 W | 972.0 W |
| Efficiency | 90.7% | 91.3% | 90.5% | 89.0% | 87.1% |
| AC Voltage | 116.7 V | 114.7 V | 112.6 V | 110.4 V | 107.9 V |
| Power Factor | 0.992 | 0.991 | 0.995 | 0.996 | 0.997 |
| Final Result | Pass | Pass | Pass | Pass | Pass |
The XFX PRO 850 W Black Edition Full Modular presented outstanding efficiency, always above the minimum set by the 80 Plus Gold certification. The 80 Plus Gold certification promises efficiency of at least 87% under light (i.e., 20%) load, 90% under typical (i.e., 50%) load, and 87% under full (i.e., 100%) load.
Let’s discuss voltage regulation on the next page.
[nextpage title=”Voltage Regulation Tests”]
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. We consider a power supply as “flawless” if it shows voltages within 3% of their nominal values. In the table below, you can see the power supply voltages during our tests and, in the following table, the deviation, in percentage, of their nominal values.
The XFX PRO 850 W Black Edition Full Modular presented outstanding voltage regulation, with the positive outputs always within 1.60% of their nominal values.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | 1.17% | 0.83% | 0.67% | 0.33% | 0.17% |
| +12VB | 1.08% | 0.50% | 0.17% | -0.33% | -0.83% |
| +5 V | 0.40% | 0.20% | 0.20% | 0.00% | 0.00% |
| +3.3 V | 0.30% | 0.30% | 0.00% | 0.00% | -0.30% |
| +5VSB | 1.60% | 0.80% | 0.20% | -0.60% | -1.20% |
| -12 V | 3.92% | 2.50% | 1.00% | -0.75% | -2.50% |
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 XFX PRO 850 W Black Edition Full Modular provided extremely low ripple and noise levels, as you can see in the table below.
| Input | Test 1 | Test 2 | Test 3 | Test 4 | Test 5 |
| +12VA | 18.4 mV | 19.6 mV | 21.2 mV | 25.2 mV | 29.2 mV |
| +12VB | 19.4 mV | 20.6 mV | 21.0 mV | 22.4 mV | 25.4 mV |
| +5 V | 10.4 mV | 11.4 mV | 11.4 mV | 12.2 mV | 13.6 mV |
| +3.3 V | 9.8 mV | 10.6 mV | 11.8 mV | 12.8 mV | 13.4 mV |
| +5VSB | 6.4 mV | 7.6 mV | 9.0 mV | 10.2 mV | 11.4 mV |
| -12 V | 18.8 mV | 19.8 mV | 19.0 mV | 23.6 mV | 28.6 mV |
Below you can see the waveforms of the outputs during test five.
Figure 25: +12VA input from load tester during test five at 846.7 W (29.2 mV)
Figure 26: +12VB input from load tester during test five at 846.7 W (25.4 mV)
Figure 27: +5V rail during test five at 846.7 W (13.6 mV)
Figure 28: +3.3 V rail during test five at 846.7 W (13.4 mV)
Let’s see if we can pull more than 850 W from this unit.
[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 protection circuits working properly. We were limited by our load tester, which can only pull up to 1,000 W, so we couldn’t test the power supply’s protections. During this test, noise and ripple levels were still extremely low, with all outputs still within their tighter-than-usual range.
| Input | Overload Test |
| +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) |
| Total | 988.4 W |
| % Max Load | 116.3% |
| Room Temp. | 42.5° C |
| PSU Temp. | 57.2° C |
| AC Power | 1,187 W |
| Efficiency | 83.3% |
| AC Voltage | 105.4 V |
| Power Factor | 0.997 |
[nextpage title=”Main Specifications”]
The main specifications for the XFX PRO 850 W Black Edition Full Modular power supply include:
- Standards: ATX12V 2.3 and EPS12V 2.91
- Nominal labeled power: 850 W
- Measured maximum power: 972 W at 46.0° C
- Labeled efficiency: 80 Plus Gold certification (87% at light/20% load, 90% at typical/50% load, and 87% at full/100% load)
- Measured efficiency: Between 87.1% and 91.3% at 115 V (nominal, see complete results for actual voltage)
- Active PFC: Yes
- Modular Cabling System: Yes, full
- Motherboard Power Connectors: One 20/24-pin connector, one EPS12V connector, and two ATX12V connectors that together form an EPS12V connector
- Video Card Power Connectors: Four six/eight-pin connectors on two cables
- SATA Power Connectors: 10 on three cables
- Peripheral Power Connectors: Five on two cables
- Floppy Disk Drive Power Connectors: Two, through two adapters
- Protections (as listed by the manufacturer): Over voltage (OVP), over current (OCP), over power (OPP), over temperature (OTP), and short-circuit (SCP) protections
- Are the above protections really available? Couldn’t test.
- Warranty: Five Years
- Real Model: Seasonic X-Series KM3 850 W
- More Information: https://xfxforce.com
- Average Price in the U.S.*: USD 160.00
* Researched at Newegg.com on the day we published this review.
[nextpage title=”Conclusions”]
The XFX PRO 850 W Black Edition Full Modular is another flawless power supply manufactured by Seasonic, targeted to users who demand only “the best.
” Its efficiency surpassed the numbers promised by the 80 Plus Gold certification at high temperatures. Noise and ripple levels were very low, and voltage regulation was outstanding, with the main positive voltages (+12 V, +5 V, and +3.3 V) within 1.2% of their nominal values. The ATX12V specification allows a 5% deviation, and we usually consider units with 3% voltage regulation as “flawless.”
Other highlights of the XFX PRO 850 W Black Edition Full Modular include the fully modular cabling system and the semi-passive mode of operation, where you can configure the power supply to turn on its fan only when you pull above 30% of its labeled wattage, and at low speed between 30% and 50% load, thereby making the power supply silent when the computer is not demanding a lot of power.
The only constructive criticism we have is regarding the name of this power supply. We think it is really confusing to have power supplies with different characteristics and different levels of 80 Plus certification using the same name.
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