Corsair CX850M 80 PLUS Bronze Power Supply Review

Although we have many company’s PC market offering top of the line components, but choice out appropriate power supply is one hardest part in entire PC build. However, narrowing down to designer and manufacturer is the most perfect way to occupy the suited product for your PC. Corsair has been in the market, since 1994, and well-known as one of the best PSU provider worldwide. In the blink of time, they became stronger in competition, especially with TX, AX and HX series PSUs, which considered as one of the highest end power supplies to date.

Corsair CX850M 80 PLUS
Manufacture Corsair
Available at View at Amazon

Corsair offers power supplies ranges from high end to low end, from premium to budgeted, Platinum to Bronze. The budget mid-end power supplies are usually popular for moderate gaming rig, i.e. Single GPU system. The CX series is one of the budget unit builds made by CWT however, with more failure rates on top and known as one of the worst in Corsair branding. Which brings CX-M refresh line power supplies in the market, released in 2015, designed for high end gaming rigs. The major difference between the two is the voltage stability that has much improved in CX850M 2015 edition, identified by Grey label on exterior.

Today, we are looking at the Corsair CX850M Bronze power supply. The CX-M basically comes in many capacities, ranges from 450W to 850W, has two different editions, 2015 and 2017. What we have in the house, is the CX-850M 2015-Edition. The unit is being designed to cater most mid-end PCs with continuous output and comes with 5 years’ warranty. The CX850M has a dimension of 150mm x 86mm x 160mm and retail package weighing at 3.3KG including box. A multi-GPU ready PSU offers 840W on +12V and 130W on +3.3v and +5.5v rails combined.

[amazon table=”2882″ link_id=”26713″]


  • Low Noise Operation
  • Multi-GPU ready
  • ATX12V v2.4 and EPS12V v2.9
  • Haswell Ready
  • Semi Modular Cabling system
  • Continuous output at 40°C

The Unboxing and Content

The Power supply comes in a well-designed, extremely compact box, featuring black grayish and yellow theme. The top of the box gives us brief overview of the product, having corsair logo and series name at top. The PSU is being pictured in the middle while the product name, warranty icon and Bronze located next to it.

The backside is being detailed. The Continuous output, modular cabling and low noise is being printed right below to the corsair logo. In the middle, a couple of graphs, exhibiting the efficiency and fan noise level; the power rating right below to it. The extreme right has the PSU dimension. Overall, it is a very compact as well as detailed box.


One of the sides has the cabling specification with images. A predefined way to memorize the cable length and quality. If you want to see the certifications and model detail, then you can have it on other side of the box. The safety certifications can be seen at lower portion: CCC represents China, EAC is Russia and KC is korea, couldn’t identify the other certifications. These are region dependent, you may or may not see all of them on your box. The extreme corner has the big, white barcode sticker contains serial number on it.

Once we open the box, we have the manual placed right on top and then there is protection layer on top of the PSU. In an open, there are cables packed in the plastic bag placed right next to it which also assisting in solid and interrupted packaging. Removing the first protection layer, we see PSU itself, with another protection layer at bottom.

The extras are the manuals and a plastic bag contains long Zip-ties and a small bag of PSU screws. The following items you will get in CX850M package:

  • PSU itself
  • Modular cables
  • Cord cable
  • Manual
  • Zip-ties & Screws

Cable and Connectors

Except the 24pin Power Cable that comes as a pre-braided cable, the rest of the cables comes with power supply are flat in nature. The Flat design of cables have now been new standard for PSUs. In this design, each wire is separately sleeved in black coating, so called flexible flat cables. Flat cables are now discerned and popular among gaming community and PC builders. One of the major advantage of this design is the ease to manage. There was time when we were dealing with beefy sleeved cables, that only brought more hard work, difficult to manage and more headaches.

The list of cable comes with the PSU:

  • 1x 24P ATX Cable
  • 4x 6+2P PCIe Cable
  • 8x SATA Cable
  • 6x Peripheral Cable
  • 2x Floppy Cable


It’s a complete black PSU with matte black finishing. The top side has a large size label, exhibiting the PSU power rating and vice versa. The most important aspect to look at, is the DC output specification, the +12V draws 850W by utilizing 70.8A. so theoretically it gives full rating.

One of the side has the Corsair designed strip that ends with black and silver color scheme. The strip has the CX850M printed on it which showcases the PSU from outside, too good. You will see this similar sort of design on other PSU, too, that released by Corsair company. The other side is completely black and has nothing but the plain black view.

Coming on the front side, we have the cabling system, Power cable ATX is coming out from the PSU along with the ATX12V CPU. Both the cables are sleeved, the old fashioned way, unlike the rest modular cables. The modular system is residing next to it, distributed in two rows. The top row has the CPU 4+4 Pin connector and Peripheral & SATA connectors. The bottom row has PCIe 6+2pin on left and again, peripheral and SATA on right side. The benefit of Semi-modular is that you can at least have the modular option in contrast to traditional Non-modular units.


The backside has the look inside round holes along with the AC input 3 pin port and ON/OFF power switch.

The fan side is also following with the black theme, the grill is black too, but tightly fixed with the screws across each end. The matte black finish on around side area. A 135mm Fan inside the PSU runs at a speed of 2084 RPM. The purpose of large fan is to bring down the noise level during normal load condition. Runs at 2084 RPM, while break down the speed at different load conditions. However, expecting to be dead silent is not way, as the RPM itself suggesting the fan to be loud. The warranty void sticker can be seen at one of the side, that if removed, warranty cannot be claimed.

Power Ratings and the Efficiency:

The corsair CX850M is compatible with at least 100V and maximum 240V for power output source. Also, the maximum ampere it requires to power on the device is 12A while minimum is 6A that could be from Extension/lead or direct switching.

The power supply has one +12V rail, +3.3V and +5V that are more concerned for PC builders. The +!2V rail is usually handle high power component, like CPU and Graphics card. CX850M is offering 70.8 Amperage on a +12V rail that should be more than enough for dual GPU gaming system. However, if the internal design is weak and the components are not capable of handling the extreme load you will face serious trouble. On the other hand, the +3.3v and +5.5v Rail are really doing nothing when the high power +12V rail has enough output.

When talk about efficiency, keep in mind the fact, efficiency in power supply mostly related to saving the electricity or energy. That is no way directly link to the power consumption of PC components. However, the better efficiency would also suggest the quality of internal design unit. Highly efficient units such as GOLD, Platinum and now the Titanium are mostly backed up with a high quality design because they have to be more efficient at mid-to-high load condition and that’s why companies these days acquiring top manufacturers to make success. The CX850M is a Bronze certification model that means, it can maximize the efficiency at 85% probably on mid-loads.

The Channel Well Technology (CWT) is being the OEM for Corsair CX850M power supply. They have also build the low wattage units like CX450M, CX 550M and CX 650M. CWT is a good name in manufacturing power supplies especially the moderate category, not much of the repute in high-quality PSUs. In this build, CWT has used Japanese Nipplon Chemi-con as the main capacitor is being rated at 470uf to deliver at 105°C.

Test Bench

  • Asrock Z170 Professional i7 Gaming
  • Intel Core i7 6700K OC at 4.5 GHz
  • Kingston HyperX Fury 16GB DDR4 2666 MHz RAM
  • Sapphire AMD R9 290 TriX 4GB GPU
  • Plextor M9PeG 256GB PCIe NVMe M.2 drive
  • Seagate 3TB 7200 RPM Hard drive
  • Samsung 850 EVO 256GB SATA III SSD
  • Corsair CX850M Bronze PSU (Reviewing Sample)
  • Noctua NH-U14S Air Cooler

The first and foremost part of this testing is the Voltage readings by using digital meter. we used Thermaltake Dr. Power II and recorded the output values in excel sheet. As for idle testing, we kept the system in no-usage mode or Idling and noted down the wattage it drawn from wall outlet. About load testing and efficiency, we have tortured the system via heavier synthetic applications, Prime95 and Heaven 4.0v combined. The processor, Intel Core i5 8400 6C/6T overclocked at @4.5GHz, and Graphics card, AMD R9 290, been kept at stock. During the tests, we took voltage values under maximum load condition and after taking into account, we readied them to show them in charts.

Moreover, we have utilized a few games to ascertain the power draw during the heavy  gameplays. This is for groups who are only interested in gaming power draw from wall. A couple of games and synthetic benchmark used to put some effective load on power supply. Note that, it is not a GPU test, the power supply needed to be put on load and in the absence of proper equipment, gaming system has been utilized.

The reason why we are not having proper equipment, the lack of funds and correspondences; it is not possible to obtain a high end testing equipment. Therefore, the procedure of testing is very limited. I got an EU Power Monitor to ascertain the wattage that pulled from the wall. In addition, a Thermaltake Dr. Power II being used to record the voltages.


In the above tests, the power supply showed power draw of about 130W on IDLE. By triggering Prime 95 & Heaven 4.0v benchmarks simultaneously we effectively reached at extensive load. The ideal load on power supply is 50-60% because an efficiency usually peaks out at mid loads. The digital meter showed us the system pulled 464W from the wall outlet as the total system power draw. This wattage is apparently passed 50% load i.e. 58% power draw out of granted 850W.

The Metro Last light is one of the heavier game on GPU and PSU. So we took that game to be tested on this power supply, to ascertain the max power draw during gameplays. We put the benchmark in a 20 runs loop and that’s actually a lot, if you ask me. As a result, the maximum power drawn from the wall outlet was 391W, which apparently, at around 47% load on the power supply.

During the wattage test, I also made sure to check the voltages under idle and full LOAD; this helps to understand the power supply’s tolerance level and stability factor. Basically, under the ATX specification, the PSU voltage fluctuation should not be more than 5%, for example, on +12v rail product, the max acceptance level should remain between 11.4-12.6 Volts. Anything below from the minimum limit would sign the PSU as being problematic.

So, looking at the chart above, the voltages are just look fine. Maintaining at 12.10v on +12V rail as a max dip on the voltage cycle, is apparently, seem good. It could be more alarming if it would reach at 11.7-11.8v but that is not the case here. Overall, the stability level seems just fine.

Fan speed and Noise

These days, power supply  manufacturer improving the fan operation by offering fanless operation during mid-loads. However, we haven’t seen anything like that in this unit. So during tests, we were noticing the behavior of fan noise. We unable to record the fan speed during our tests but it rated to cool the components at speed of 2084 RPM, which is quite much for a PSU fan. However, specs sheet tells us this fan generate 19.5 dBA till 50% load and 37.0 dBA on 100% load condition. A slightly high, especially in the competition.

[pros_cons id=”7″ asin=”B00OVCJKWC” ]

Corsair CX850M offers a great deal of capacity to PC builders. A well designed box that has all the necessary features that completes 850W power supply. However, it’s a low efficiency certified model that maxed out 85% and that’s quite a margin when comparing in platinum and Bronze competition. This also shrinks if you’re not into saving energy. Besides having an elegance look, the CX850M offering a semi-modular cabling design, a big plus for people who are coming from non-modular. The cables are long, but not quite much to reach the long destination components, if required. In Full tower chassis, you might need to sacrifice the desired routing.

There was nothing wrong in CX850M in terms of power delivery to components and DC output. Here, the capacity is not a problem by any mean, because it’s already 850W with 70A on +12V single rail, and if you’re on single High-end GPU configuration, it’s just a lot of capacity to be used. This apparently, one future proof upgrade for dual-GPU configuration system, hell yes! Besides, a noteworthy feature is that the PSU is capable to provide the continuous output at rated power ratings at 40°C unlike the previous CX series that had only 30°C continuous output. It’s quite an improvement over former series. In the CX850M, the power drawn from wall outlet reached 464W which is completely normal on 220V AC Input. We haven’t see any abnormal behavior in voltages during testing. All the requisite voltages have been optimal.

Selling at $116 US Dollar (at the time of review) on Amazon, the CX850M displays a nice build that not only offers future proof capacity but a great looking exterior too. Comes with 5 years of warranty, Corsair has put a good, solid trust in its bronze unit being capable to deliver power at high temperature i.e. 40°C and also has low noise output. Considering few points: Corsair PSU availability, warranty backup of 5 years with hefty 850W power output, the product is a good value for money.

Note that, CXM series with green label is almost discontinued, so all you get is the CX850M neutral-grey, 2015 edition. Do not confused yourself with old series.

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I am a tech reviewer who loves to play with the hardware and do an in-depth analysis of the hardware for the content creation. I have over 120 contents to my credit and this number is ever growing. Besides, I love to assemble PCs and do troubleshooting.

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