Corsair HX850W is a power supply with modular cabling system and high-end components promising up to 90% efficiency, launched to compete with Antec Signature series and Seasonic M12D series. Let’s see if it survives our tests.

It is very important to notice that Corsair HX750W, HX850W and HX1000W have nothing to do with other models from this same series. They use a complete different (and better, by the way) design using a DC-DC converter to generate their +5 V and +3.3 V outputs, like Antec Signature series and Seasonic M12D series. These HX models are manufactured by CWT, while other models from HX series are manufactured by Seasonic. Why Corsair kept the same name is a mystery. In our opinion they should have used a different name so consumers would know they are facing a different product class, targeted to users looking a power supply with high-end parts and very high efficiency.

Corsair HX1000W uses two transformers inside, while HX850W and HX750W use only one.

click to enlarge
Figure 1: Corsair HX850W power supply.

click to enlarge
Figure 2: Corsair HX850W power supply.

HX850W is somewhat long, being 7 3/32” (18 cm) deep, using a 140-mm fan on its bottom and featuring active PFC, of course. It also features a single-rail design.

It comes with a modular cabling system, but the main motherboard cable (20/24-pin), the ATX12V/EPS12V cable (two ATX12V connectors that together form an EPS12V one) and two six/eight-pin auxiliary power cable for video cards come from inside the unit. These cables are protected with nylon sleevings that come from inside the power supply housing.

The modular cabling system has ten connectors and HX850W comes with ten cables plus two adaptors to convert standard peripheral power plugs into floppy disk drive power plugs. The cables included are:

• Four auxiliary power cables for video cards, with one six/eight-pin connector on each one of them.
• Three SATA power cables with four plugs each.
• Three peripheral power cables with four plugs each.

The number of cables and connectors available is really impressive. With six auxiliary power connectors for video cards you can easily install up to three very high-end video cards under SLI mode without using any kind of adaptor (each video card from this class requires two auxiliary power connectors).

The main motherboard cable, the ATX12V/EPS12V cable and the video card cables are long, measuring 23 5/8” (60 cm), so you probably won’t have any trouble using this power supply on a big full tower case. Peripheral and SATA power cables have a distance of 15 ¾” (40 cm) between the end that goes on the power supply and the very first connector on the cable. The distance between each connector on these cables is of 5 1/8” (13 cm).

The main motherboard cable use 16 AWG wires, which are thicker, while all other wires are 18 AWG, which is the correct gauge to be used.

click to enlarge
Figure 3: Cables.

Let’s now take an in-depth look inside this power supply.