Cooler Master M850 Power Supply

Power Supplies, Reviews

Coolermaster M850 Power Supply Review


Computers over the past few years have gotten very power hungry. With SLI and Quad Cores now being used in many computer systems, the increasing need for more power is apparent. However, the need for need for more power isn’t the only reason us hardware enthusiasts are buying bigger and better PSU’s. The need for a silent system has really hit off over the years and many enthusiasts are replacing their box standard powers supply with one that is marketed as ‘Silent’. One new power supply out on the battlefield is the Cooler Master M850- labelled as Ultra Silent and of High Efficiency. Well, let’s just see shall we…


  • World’s first six +12V rails for better power distribution in Quad-SLI and 2 ways server system
  • Modularized cable design to eliminate clutter and improve airflow inside the chassis.
  • Four 6 pin / Two 8 pin PCI-e connectors offer great future upgradeability
  • Compliance with the newest Intel standard ATX 12V V 2.3
  • Compliance with the newest SSI standard EPS 12V V2.91
  • Ultra-silent operation with intelligent 135mm fan speed control (< 16dBA)
  • Eco-design for energy and money saving by Active PFC.(>0.99)/ high efficiency(>85%)
  • Multiple protection function provides full-scale protection for your components
  • Safety Certification : CE, cUL, TUV, NEMKO, BSMI and FCC
  • Five-year warranty


The Cooler Master M850 arrives in a thick cardboard box which has a large photo of the PSU on the front, specifications on the side and features written in 17 languages on the back. This is all the information you’d need before burning a hole in your pocket on a power supply.

Coolermaster M850 Power Supply Review Coolermaster M850 Power Supply Review

Opening the box up, there is thick (2cm) foam protecting the PSU at all sides to stop it being damaged during delivery. This padding is perfectly adequate and is definitely enough to keep the Cooler Master safe.

Coolermaster M850 Power Supply Review

Inside the box is:

  • Cooler Master M850
  • Power Cable
  • Multilingual Instruction Manual
  • Cables in a rigid fabric folder
  • Cooler Master Bottle Opener Key ring
Coolermaster M850 Power Supply Review Coolermaster M850 Power Supply Review

Cooler Master M850

This product is dark grey in colour with a chromed mirror finish. In contrast with the bright green and blue modular sockets it looks awesome.

Coolermaster M850 Power Supply Review Coolermaster M850 Power Supply Review

At the front of the power supply – – where the power cord plugs in – – there is a honey comb look. This is where all the hot air is released from. Fortunately though, there is no noisy 80mm whirring fan here, so hopefully it’ll be quiet. Also, there seems to be no power switch at the back. Instead, there is an LED which lights up green when the M850 is active and red when it’s inactive. Cooler Master says that the reason for not including a switch is because when you switch your PSU from the back, a current gets trapped. After a hundred or so switches, the current will damage the unit and so it will not work. So Cooler Master has excluded the switch, allowing the power supply to last a lot longer.

Coolermaster M850 Power Supply Review Coolermaster M850 Power Supply Review

On the sides of the Cooler Master are the power specifications listed neatly in a table.

Coolermaster M850 Power Supply Review

At the rear are all the sockets where the modular cables plug in. The sockets for 6 pin PCI-E are green in colour and the sockets for 8-pin PCI-E are blue in colour. The rest of the sockets are black. Even though this PSU is modular, there are still some cables running from this product.

Coolermaster M850 Power Supply Review

The underside of the M850 has a 135mm fan which aids in stopping the fan from slicing your fingers. Why you’d want to stick your fingers into a running power supply I don’t know…

Coolermaster M850 Power Supply Review

The Cables

All the cables are braided in black braiding, allowing for a tidier look inside your case.

Coolermaster M850 Power Supply Review

Coming from the PSU (not modular) are a 24-pin ATX connector, a 4-pin CPU connector and an 8-pin CPU connector. Unfortunately, as a 24-pin ATX connector is used and not an ordinary 20-pin type, you will need to check compatibility before upgrading to this PSU as it appears its not backwards compatible.

Altogether there are a total of 10 modular cables. The available connectors are:

  • M/B 24 Pin x 1
  • CPU 4 Pin x1
  • CPU 8 Pin x 1
  • PCI-E 8 Pin x2
  • PCI-E 6 Pin x 4
  • 4 Pin Peripheral x 10
  • SATA x 6
  • 4 Pin Floppy x 2

Note that there are four 6-pin PCI-E connectors, so SLI users will be able to hook up their SLI cards to both powers connectors.


Coolermaster M850 Power Supply Review

To test power supply’s, its pretty simple. We hook up the power supply to our current test rig and leave it idle for an hour. After that hour, when the computer is fully idle, we measure the voltages of the 12V, 5V and 3.3V rails. Once these results are recorded, we load the power supply as much as possible and try to get near its maximum power output. We then take the recordings again, at load voltages.

Test Rig

Processor Intel C2D E6750 @ Stock
Motherboard Asus P5K Premium 775
RAM Corsair XMS2 6400 2GB (2x1GB)
HDD Western Digital SE16 500GB SATA
Graphics Card XFX 7900GS 256MB


Rail Idle Load
12V 12.21V 12.12V
5V 5.06V 5.08V
3.3V 3.35V 3.31V

All the rails seem to perform very well. The 12V rail is out by 0.21V, however at load voltages, it performs a bit better. This isn’t really something to be worried about though as it’s only out by a very small amount and won’t affect your system.


The fan inside the M850 is quiet, although I wouldn’t label it as ‘ultra silent’ which the box suggests. It’s quiet enough for it to be not heard over the noise of your other case fans. However, it is much quieter than many PSU’s which have both 120mm and 80mm fans- so it is a wise upgrade.


The Cooler Master retails at £110; this is the average price for a power supply in this performance band.


The Cooler Master M850 is certainly a good performer with a stable 12V, 5V and 3.3V rail. However, the “six 12V rails” which Cooler Master heavily boast about do not appear to affect the performance much and I’ve seen better offerings from PSU’s with only 2-4 rails. Noise levels from the fan were also very suprising, with it being a little louder than Cooler Master state as ‘ultra silent’, however it was certainly quiet enough not to be heard over the humming from other case fans. Appearance wise, the M850 is a good looking power supply, however as PSU’s are normally located at the top of cases, this shouldn’t be looked upon as something which needs to look good. Although, the braided cables really do help in both appearance and cable management throughout your case, so they are an important factor in PSU decision.

However, there was one small downside to the PSU, it doesn’t support CPU’s which rely on just the 20 pin connector. Although i’m pretty sure most users which actually need 850W of power will not be using a 24 pin.

Altogether, I think the Cooler Master M850 is a great power supply in terms of efficiency, noise and stability – – making this PSU a certain consideration for anyone wanting an 850W power supply.

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