The BitFenix Whisper M 450W & 850W PSU Review

BitFenix is a comparatively new company that quickly became an established brand name via their PC case designs. Today BitFenix is still focused primarily on cases but the company is slowly diversifying, offering supplies for case mods, audio products, and power supply units (PSUs). Ever since the company’s founding in 2010, we reviewed several of their case designs, but not any of their other products. Today we are having a look at their recently released ATX PSU series, the Whisper M.

The Whisper M is not BitFenix’s first attempt to diversify towards the PSU market. Their first attempt was about three years ago with the Fury series, a PSU series that heavily weighted towards aesthetics and with a relatively hefty price tag at the time of its release. This time around BitFenix is taking a somewhat different approach, trying to balance performance with aesthetics, all while maintaining a competitive price tag, especially in a very competitive market.

The Whisper M series consists of five units ranging from 450 to 850 Watts, in 100 Watt steps. In this review we are having a look at the top and tail of the series, the 450W and the 850W units. Both units are fully modular, they boast impressive on-the-box performance specifications, they are 80Plus Gold certified and get that rating at 50 °C, all while parading with a 7-year warranty. The Whisper M units also have a multi 12V rail design, which is something that we have not seen being implemented in quite some time. The MSRP pricing is $69 and $119 for the 450W and the 850W units respectively, which is be more than reasonable if the units prove to be good performers.

The company supplies the Whisper M series in an aesthetically simple but practical cardboard box. Although the artwork is limited to a partial picture of the unit itself, the rear and sides of the box are full of graphs and charts that depict all of the unit’s core features. One could notice that the text could use some editing by just looking at the front of the box, where it reads “Silence Perfromance” (two nouns, one of them misspelled). The walls of the box are very strong and the unit is packed between thick polyethylene foam pieces that are offering ample shipping protection.

Most likely in an effort to keep the costs low, BitFenix supplies only the basics alongside with their Whisper M PSUs. Inside the box we only found the necessary AC power cable, a few cable straps, four black mounting screws and a basic user’s manual (with the same spelling error). Both units share the exact same bundle, only the number of the supplied modular cables differs.

All of the Whisper M units are fully modular, with “flat” ribbon-like cables. The wires and the connectors are all entirely black. An interesting feature here is the bulky connector of the 24-pin ATX cable. The large plastic cover is not there solely for aesthetic purposes but it actually hides three solid-state capacitors that are being used for extra ripple suppression. This is the first time that we have seen the designer of a PSU employing capacitors outside of the unit’s body. 

Physically, the 450W version of the Whisper M is almost entirely identical to the 850W version. The only real way to tell the two units apart is to look at the large stickers with their electrical specification at the top of the chassis or know the cable layout variations in the series. Both units are built in a standard-size ATX chassis that is 160 mm long and sprayed with a matte black paint. The matte paint is very well applied but it is easy to scratch and heavily prone to fingermarks.

A square opening at the bottom of the chassis reveals the cooling fan and is covered with a finger guard that uses a parallel grating. The only round part of the metallic design is the company’s badge over the fan’s engine. Black/Yellow stickers decorate both sides of the PSUs, without any mention of any figures or model numbers. Only the large stickers at the top of the chassis has the full electrical specifications of the PSU printed on it.

The front side of the PSU is littered with the connectors for the many modular cables. Here the 850W version has two connectors more, for the two additional PCI Express cables that it has.

As expected, considering the large difference in power that the two PSUs have, their first major difference is the 135 mm cooling fan. Both fans are supplied by Martech, a rarely-seen Chinese manufacturer, and both are of the same series. The 450W version comes with the DF1352512SEMN and the 850W version employs the DF1352512SEHN, with the main difference being their maximum rotational speed – 1500 RPM and 1800 RPM respectively. Both are using “Hydro” bearing engines, which are advanced forms of regular sleeve bearings.

The OEM behind the Whisper M units is Channel-Well Technology (CWT), a company that we are very familiar with. However, this is a design that we have never encountered prior to this date. First and foremost, it is worthwhile to mention that both PSUs are based on the same platform, meaning that all of the different versions of Whisper M should all be on this platform (it would be rare for a mid-powered unit to differ). A quick glance reveals that there are no great differences between the two PSUs other that the sizing of some of the components. We were actually bewildered to see that the 850W version is using the same heatsinks as the 450W version does, despite having nearly twice the power output, hinting that the employment of the more powerful fan was more of a necessity and less of a precaution.

The internal design of the Whisper M units is very clean, with minimal use of wires at all. The secondary board with the modular cable connectors is soldered directly onto the main board, hinting that CWT has designed this particular platform for modular-only PSUs. We can see that both units are sharing the same filtering stage, with four Y capacitors, two X capacitors, and two filtering inductors. The heatsink of the input conversion bridge is identical, but the bridge itself is (vastly) different between the two units. Specifically, the 450W version employs a GBU606 that is capable of 6 Amperes, whereas the 850W version is making use of an oversized GBU15L06, a bridge capable of 15 Amperes.

BitFenix Whisper M 450W – Internal View

Another major component difference between the two units are the PFC components, with the 450W unit using a Nichicon 330μF capacitor, whereas the 850W version has a Nippon Chemi-Con 680μF capacitor installed. The APFC inductor is also notably larger and the active components are significantly more powerful. Two transistors form a relatively simple half-bridge primary inversion side with its efficiency boosted by an LLC resonant converter. The four secondary side conversion stage transistors that generate the 12V output are attached to the underside of the main PCB and cooled by the silvery heatsinks next to the main transformer. The 3.3V and 5V outputs are generated by DC-to-DC circuits found on the small vertical PCB.

BitFenix Whisper M 850W – Internal View

It is worthwhile to notice that both units are using filtering capacitors of the same type and size at the secondary side for filtering. Nippon Chemi-Con supplies the electrolytics and most solid-state capacitors, with the rest of the solid-state capacitors coming from Nichicon.

For the testing of PSUs, we are using high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M  40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs – 2014 Pipeline post.

Both the 450W and the 850W version of the BitFenix Whisper M PSU honored their 80Plus Gold certification without issues. The 450W version actually fared a little better, with an average nominal load range (20%-100%) efficiency of 91.2%. It is only slightly higher than that of the 850W version (91%), but we can see the 850W version only barely surpassing the 92% mark at 50% load, where the 450W version exceeded it with ease, peaking at 92.5%. We can also notice that the 450W model is substantially more efficient with loads lower than 300 Watts. This is not an issue of any kind; the narrow power range of the 450W model simply allows it to perform much better when lightly loaded. The powerful 850W model technically reaches its nominal load range with a load of 170 Watts and above, in the range where the 450W model is already moving towards peak efficiency.

With loads lower than 300 Watts, the higher efficiency of the 450W model…