In the past decade, when ATI CrossFire and NVidia SLI technologies appeared, as well as high-performance video cards that support them, a massive boom in powerful power supplies began. Consumers were more than willing to buy devices that actually exceeded the system’s power consumption by two, three, or even four times. It reached the point of absurdity and systems based on the legendary Core 2 Quad Q6600 and a GeForce 8800 GT-level card were equipped with an 850-1000 W unit. Fortunately, users soon realized that mainstream gaming PCs only consume 200-400 watts at peak and shifted their attention to the energy efficiency and noise level of the purchased device. In the end, «kilowatts» began to be used for their intended purpose — to power tandems of a couple of powerful video cards, and given the decrease in power consumption in modern graphics accelerators, 850-watt solutions may well be enough for such assemblies. For example, Raidmax RX-850AE-B of the Cobra series.

Raidmax Cobra RX-850AE-B

Raidmax Cobra 850W (RX-850AE-B)

Recently, we have already considered the Cobra series power supply, and not just one, but all the differences between them were in appearance, “semi-modular” design, delivery package and platform used, and, of course, power. Our copy belongs to the older model range and comes in an original plastic container with a handle, on the sides of which electrical characteristics and the number of certain connectors are painted.

Inside there is an additional tray, on which some of the accessories are located, the rest, like the power supply itself, are already located under it.

Raidmax Cobra RX-850AE-B

In the package, the user will find several Velcro ties, a set of detachable cables, two sets of screws for fastening, including a knurled head, a power cord and a rubber seal on the edge of the unit to reduce the transmission of vibrations to the case of the system unit. At this price, the Raidmax Cobra 850W is a very worthy kit.

Raidmax Cobra RX-850AE-B

Part of the power cables are stationary, i.e. do not come unfastened, and are enclosed in a black and yellow braid. The processor power cord allows you to connect to two connectors on the motherboard, which can be useful for extreme overclocking or a dual-processor system.

Main loops:

  • one to power the motherboard (55 cm);
  • one with two 8-pin connectors (4+4) for processor power (61+25 cm);
  • one with two 8-pin connectors (6+2) for video card power supply (50 cm).
Raidmax Cobra RX-850AE-B

The rest of the loops are as follows:

  • two with one 8-pin (6 + 2) connector for powering PCI-E video cards (50 cm);
  • three with three power connectors for SATA devices and one for IDE (50+15+15+15 cm);
  • one with three power connectors for IDE devices and one for FDD (50+15+15+15 cm).
Raidmax Cobra RX-850AE-B

Unlike the previously reviewed RX-1200AE-B, our ward will not allow you to connect more than two voracious video adapters. It is understandable, such monsters can easily «eat» up to 300 watts each. But under the condition of less appetite, the block will power three, or even four, graphics accelerators without any problems. All cables are also encased in black and yellow nylon braid.

Externally, the power supply looks original, not least due to the proprietary hexagonal stamped grille. This has already been seen previously in the Raidmax device with RGB backlighting. The depth of the case is 165 mm.

Raidmax Cobra RX-850AE-B

On the inner wall there are six connectors for attaching detachable cables, moreover, they are larger for video cards, so it will not be possible to confuse them.

Raidmax Cobra RX-850AE-B

The RX-850AE-B can easily power a load of almost its rated power of 840 watts. The combined power of low-voltage lines is 100 W, which is enough in modern realities.

Raidmax Cobra RX-850AE-B

For standby voltage and -12V, 3 and 0.4 A are provided, respectively.

Raidmax Cobra RX-850AE-B +3.3V +5V +12V1 –12V +5Vsb
Max. load current, A 20 20 570 0,4 3
Combined power, W 100 840 3,6 12,5
Total maximum power, W 850

Of the protections, the manufacturer promises the following: from short circuit, overcurrent and power, from high and low output voltage. There is an active PFC module and the ability to work in a wide range of mains voltage.

Inside was the same platform as the older model with a capacity of 1200 watts. Among its advantages, one can single out a synchronous rectifier at the output and independent voltage stabilization.

Raidmax Cobra RX-850AE-BRaidmax Cobra RX-850AE-B

The installation is still tight, but the number and rating of the components already corresponds to the power of 850 watts.

Raidmax Cobra RX-850AE-B

The input filter is still assembled with all the necessary components, including a relay that turns off the thermistor, which limits the charge current of the input capacitance. But the protective partition between the output circuit and the wires is no more.

Raidmax Cobra RX-850AE-B

Power elements are cooled by large radiators with good fins. For diode assemblies, an additional small cooler is provided, which relieves the thermal load at the extreme bridge. A temperature sensor is installed on the radiator of the synchronous rectifier, pressed with a proprietary bracket.

The role of the control controller is assigned to the CM6802TBHX chip, located on a separate board near the inner wall of the power supply, next to which there is another board with the PS223 supervisor. The standby voltage is generated by the A6069AH microcircuit.

Low-voltage channels are based on a pair of DC/DC converters controlled by APW7073 PWM controllers installed under the synchronous rectifier heatsink.

Raidmax Cobra RX-850AE-BRaidmax Cobra RX-850AE-B

The input circuit has two 270 uF capacitors with an operating voltage of 420 V manufactured by JunFu, as well as other electrolytic capacitances in other circuits.

The board with detachable cables has a couple more JunFu capacitors and some SMD elements.

Raidmax Cobra RX-850AE-BRaidmax Cobra RX-850AE-B

The quality of the soldering is excellent, there are no smudges and “snot”, there are not even flux residues.

Raidmax Cobra RX-850AE-B

The device is cooled by a 135mm PY-13525M12S fan manufactured by PowerYear. It is based on a slip sleeve and is connected with a two-pin connector. On the side of the outer wall of the power supply, the fan has a grill, which is designed to weaken the air flow in this place and thereby direct it to hotter components on the other side.

Raidmax Cobra RX-850AE-B

When the system starts and under light load, it rotates at a speed of 705–730 rpm, while it works quite quietly, but as soon as you start the game with a couple of voracious cards, its speed rises to 1235 rpm and it makes itself felt. A load that slightly exceeds the rating of the device already increases its speed to 1756 rpm and the fan can hardly be called quiet.

Test Methodology

It is difficult to carry out full testing without an appropriate stand, so the power supplies were tested using a conventional system assembled from the following components:

  • processor: Intel Core i7-6700K (4.0@4.5 GHz);
  • motherboard: ASUS Maximus VIII Formula (Intel Z170);
  • Cooler: Prolimatech Megahalems;
  • RAM: HyperX HX430C15PB3K2/16 (2×8 GB, DDR4-3000, 15-16-16-35-1T);
  • video cards: GeForce GTX 1080;
  • drive: Kingston SSDNow UV400 240GB (240 GB, SATA 6Gb/s).

Testing was carried out in the Windows 10 x64 environment on an open stand. To create a gaming load on the system, the Valley benchmark was used with maximum graphics quality, and for additional load, LinX 0.6.7 was launched in parallel.

Also, for maximum load, the following system was assembled:

  • processor: Intel Core i7-975 (3.33@4.02 GHz, Bclk 175 MHz);
  • motherboard: ASUS P6T7 WS SuperComputer (Intel X58);
  • cooler: Noctua NH-D14;
  • RAM: Kingston KHX2000C8D3T1K3/6GX (3×2 GB, DDR3-2000@1750, 8-8-8-24);
  • video cards: ASUS ENGTX295/2DI/1792MD3/A and Inno3D GeForce GTX 295 Platinum Edition (GeForce GTX 295);
  • hard disk: Samsung HD502HJ (500 GB, 7200 rpm, SATA-II).

Here testing was carried out in the Windows 7 x64 HP environment on an open bench. To create a load on the system, we used the Tropics benchmark with activated 4x anti-aliasing and 16x anisotropic filtering, while the video adapters worked in SLI mode. Another test was carried out with the launch of the OCCT 3.1.0 utility in full screen mode.

To measure the total power consumption of the system, the Seasonic Power Angel was used, which can also measure the power factor, voltage and frequency in the network, the consumed current and the amount of energy spent per unit of time. Net power consumption calculated based on 80 Plus certification — i.e. possible efficiency of the device. Errors in such calculations can be 5%. The voltages were checked with a UNI-T UT70D digital multimeter.

In addition, we decided to slightly expand testing by taking temperature readings inside the power supply, fan speed.

The temperature was measured using the Scythe Kaze Master Pro panel, the sensors of which were located on the radiators inside the block and at a distance of 1 cm in front of the fan (#1) and behind the outer wall (#2).

Raidmax Cobra RX-850AE-B

For fan speed results, a UNI-T UT372 non-contact tachometer was used. The maximum speed was fixed for each of the power supply testing modes.

It should be borne in mind that such a technique at this stage is far from ideal and will be supplemented and changed as it is used.

Test results

The obtained data are entered in the table. In brackets for voltage are percent deviations from the norm, for power consumption — the approximate net load on the power supply.

GTX 1080 (LGA1151) GTX 1080 (LGA1151) GTX 295 SLI (LGA1366) GTX 295 SLI (LGA1366)
Mode Idle Burn, Game+LinX Burn, Game Burn, OCCT
Power consumption, W 38,4 (~31) 346 (~300) 667 (~600) 1053 (~930)
Line +3.3V, V 3,33 (+0,9) 3,33 (+0,9) 3,27 (–0,9) 3,26 (–1,2)
Line +5V, V 5,03 (+0,6) 5,03 (+0,6) 5,02 (+0,4) 5,01 (+0,2)
Line +12 (MB), B 12,03 (+0,25) 12,01 (+0,1) 11,97 (–0,25) 11,96 (–0,33)
Line +12 (CPU), V 12,03 (+0,25) 12 12,06 (+0,5) 12
Line +12 (VGA1), B 12,03 (+0,25) 12,01 (+0,1) 12 11,98 (–0,16)
Line +12 (VGA2), B 12,03 (+0,25) 12,04 (+0,33) 12,03 (+0,25) 11,97 (–0,25)
Fan rotation speed, rpm 705 732 1235 1756
Thermosensor No. 1 24,7 24,6 25,4 25,4
Thermosensor #2 27,1 30,1 31,1 32,3
Thermosensor No. 3 30 39,5 43,1 54,6
Thermosensor No. 4 29,3 43,1 52,9 62,6

Well, very good performance, minimal drawdowns and good stabilization of all voltages, except for +3.3 V, but everything is within normal limits. The speed of the fan is bewildering, given the low temperatures of the radiators of the power elements. Perhaps the available component base requires enhanced cooling.


The considered Raidmax RX-850AE-B power supply will be an excellent choice for an economical or undemanding user. At its modest cost, as for an 850-watt device, besides with the 80 Plus Gold certificate, it has an extended package and excellent characteristics. It is unlikely to be suitable for a quiet system, but this Cobra will easily fit into a tandem of a pair of powerful reference video adapters. When using less voracious graphic accelerators, the latter can be brought up to 3-4 pieces, which will be appreciated by the modest “prospectors” of the cryptocurrency fever.

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