External Appearance

Visually, the Power Zone 850W CM PSU is certainly unique. Plastic frames cover the front and rear sides of the unit, while the series logo is embossed on the sides of the black chassis. The fan guard is not a typical circular grill but instead uses an array of parallel wires. A metallic badge is placed above the fan's engine, denoting the unit's maximum power output, and the sticker with the electrical specifications can be seen on the top of the chassis.

The visual enhancements however also add bulk, making the chassis 175mm deep, considerably deeper than a typical ATX PSU, thus the Power Zone 850W CM is incompatible with a large number of PC cases. The plastic frames also add spacing around the main PSU chassis, which is why be quiet! includes longer screws than normal.

For the cabling, this is a fully modular design, with no hardwired cables. Many modular PSUs will have hardwired 24-pin and ATX12V/EPS12V cables as these are always required, but by making a fully modular case it opens the door for shorter cable harnesses. Unfortunately be quiet! doesn't currently sell any shorter cable sets for the Power Zone series, but that may change.

Internal Design

One of this product's most important features is the use of a "Silent Wings" 135mm fan. These fans have been designed by be quiet! with ribbed blades that are supposed to reduce aerodynamic noise; however, this particular model is not very quiet, as it has a maximum speed of 2900RPM. It takes a very efficient 850 Watt unit to allow the use of a low-speed cooling fan, and with a Bronze rating this particular line benefits from better airflow and cooling. The fan does use a high quality fluid dynamic bearing, which will help to reduce noise, but as we'll see in a moment the PSU is still clearly audible at higher loads.

The OEM behind the Power Zone 850W CM is Fortron Source, a company we usually find behind middle and lower range products. This PSU uses a textbook filtering stage, with four Y capacitors, two X capacitors, and two filtering inductors at the back of the receptacle and on the main board. Two primary rectification bridges work in parallel, each bolted onto its own small heatsink next to the large APFC coil. The two 220 μF APFC capacitors are rated for operation at 105 °C and are supplied by Teapo. Actually, almost every single capacitor in the Power Zone 850W CM, electrolytic and polymer alike, is supplied by Teapo, with the weird exception of a single small Nippon Chemi-Con electrolytic capacitor on the distribution PCB.

Strangely, although the platform has very good potential and implements modern technologies, such as an Active Clamp topology and DC-to-DC conversion circuits, be quiet! uses very basic active components (i.e. transistors) on the primary inversion and secondary conversion levels. This reduces the overall efficiency of the Power Zone 850W CM down to 80 Plus Bronze levels. If they would have chosen active components with lower resistance and/or better behavior, this design could easily qualify for 80 Plus Silver or Gold status.

The assembly quality of the Power Zone 850W CM is excellent, especially for a Fortron Source design. It is a clean design, with black glue used to mechanically secure the components and minimize high frequency vibration noises. The soldering job is not perfect, as we found a few joints where the use of solder was a bit too generous, but it is very good nonetheless.

Introduction, Packaging & Bundle Cold Test Results
Comments Locked


View All Comments

  • inighthawki - Thursday, August 14, 2014 - link

    Sorry, that should read:

    "whether or not to get a second *GPU*"
  • Daniel Egger - Thursday, August 14, 2014 - link

    > 2) PSUs generally get their best efficiency while running at 50-60% load. So having a 750W PSU to power a 400W system provides the best efficiency. (Granted I realize for many this is a silly point, since the extra cost of the PSU itself generally will outweigh any cost savings, but maybe they like to be green, or just have the money)

    Your reasoning is flawed because a typical (even gamers) PC spends considerable amounts of time *way* below the maximum power rating where you'll immediately loose any advantage you would gain from having the maximum rating at the maximum efficiency point big time, especially if your system idles a lot and drops below the miraculous 20% mark.

    But with a 400W system a few percent efficiency more or less really don't matter any more as there's definitely no greenness to be had anymore...
  • DanNeely - Thursday, August 14, 2014 - link

    As a distributed computing (Boinc, primarily Einstein at home) participant, I suspect my system probably spends <95% of its operating time at full load; and my average load while gaming is probably below the non gaming average because the threshold where I have to GPU compute while playing to keep good FPS is lower than what's needed to heavily load the GPU. (Games and Compute are a lot worse at sharing GPU resources than their CPU equivalents.)
  • inighthawki - Thursday, August 14, 2014 - link

    Fair point.
  • Flunk - Thursday, August 14, 2014 - link

    It looks like they spent a good potion of the budget on appearance. Middling electronics and a loud fan don't impress me for the price. Some low end units are built better than this and I personally don't care what power supplies look like, in most cases you don't even see it.
  • Essence_of_War - Thursday, August 14, 2014 - link

    Sidenote on be Quiet's fans, is there some specific reason that they seem to use non-standard fan sizes? This unit uses a 135mm fan, and their HSFs are made for 130/135mm fans as well.
  • DanNeely - Thursday, August 14, 2014 - link

    For the PSU, it's the biggest size that will fit. Meaning that all else equal, it gives the most air movement for the least noise. On the heat sinks I'm not sure why they wouldn't just edge up to 140mm unless it's to exploit volume discounts from their supplier by using the same fans for both products.
  • piroroadkill - Thursday, August 14, 2014 - link

    I thought the 135mm fan in PSU thing was because Zalman has a patent on 140mm fans in power supplies.
  • piroroadkill - Thursday, August 14, 2014 - link

    Actually, I'm going to correct myself, because I don't think it's Zalman. I posted the same thing in 2011, and someone said it was HEC that has the patent.
  • DanNeely - Thursday, August 14, 2014 - link


    That's even more appalling than the "standard PC architecture feature on a smartphone" patents because I can't imagine any way that "use the biggest fan that will fit" could be obfuscated into something that a kindergartener, never mind a patent office reviewer, couldn't realize was trivial.

Log in

Don't have an account? Sign up now