Bitfenix Whisper Series 550W PSU Review

Bitfenix recently released its Whisper PSU family, which, as it name implies, promises quiet operation. This review focuses on the 550W model, offering 80 PLUS Gold efficiency and fully modular cabling.

Tom's Hardware Verdict

An overall great PSU with a down to earth price. Bitfenix should be proud of its Whisper line, which meets eye-to-eye the toughest competition in the Gold efficiency category. You can't go wrong with the BWG550M, it is as simple as that.


  • +

    Good price

  • +

    Full power at 46°C

  • +

    Full protection set

  • +


  • +

    Ripple suppression

  • +

    Load regulation

  • +


  • +

    Build quality

  • +

    Fully modular

  • +

    HDB fan (with not so high lifetime though)

  • +

    Flat, stealth and pretty long cables

  • +



  • -

    Hold-up time

  • -

    ATX cable's connector is tough to connect (to the PSU side)

  • -

    5VSB efficiency

Why you can trust Tom's Hardware Our expert reviewers spend hours testing and comparing products and services so you can choose the best for you. Find out more about how we test.

BWG550M Power Supply Review

Bitfenix's rookie PSU effort was its Fury Gold family, based on a not-so-competitive FSP platform. High-quality, individually sleeved cables and good looks weren't enough to make the Fury Gold stand out in a sea of tough competition priced similarly. It seems as if Bitfenix learned from its mistakes though, and the company's second PSU line, called Whisper, is more practical with attractive retail pricing.

The Whisper family currently includes five members with capacities ranging from 450W to 850W. They're all 80 PLUS Gold-certified, feature fully modular cabling, are equipped with HDB fans, and employ multiple +12V rails. Channel Well Technology (CWT in short), which enjoys increased popularity thanks to its collaboration with Corsair, manufactures the platform.

The 550W model, officially referred to as BGW550M, is on our test bench today. It has enough capacity to handle efficiently a gaming PC with one high-end graphics card. As we've mentioned in the past, modern GPUs tend to be more efficient than prior generations, so even lower-capacity power supplies accommodate the needs of very fast hardware. Of course, under overclocking conditions, power consumption can easily get out of control. So leave yourself plenty of headroom when you plan a PSU purchase if aggressive tuning is a priority.


In addition to Gold-rated efficiency and modular cabling, the BWG550M also features a 50°C temperature rating for continuous full load delivery. This is a clear indication of the high-quality components inside. Moreover, CWT equips it with a full suite of protection features that even include over-temperature protection.

Active cooling is handled by a hydro dynamic-bearing fan that doesn't enjoy a very long lifetime. Usually good-quality HDB fans can exceed 50,000 hours, while sleeve-bearing ones reach 30,000. According to a test report that fell into our hands, the DF1352512SEMN has a 30,000-hour lifetime at 25°C, meaning that it is actually on par with a good sleeve-bearing fan. We expected a higher lifetime, that's for sure.

The BWG550M's dimensions are compact, given its 16cm length. Moreover, a seven-year warranty isn't bad at all.

Power Specifications

Swipe to scroll horizontally
Max. PowerAmps20202525302.50.3
Total Max. Power (W)550

There are three +12V rails. The first two are rated at 25A, while the third one is a little stronger with 30A maximum current on paper. In real life, the OCP triggering point is set a bit higher on all +12V rails and much higher on the minor ones. This is done on purpose, of course, to let the PSU handle increased transient loads that'd normally trigger OCP without a problem.

Cables And Connectors

Swipe to scroll horizontally
Modular Cables
DescriptionCable CountConnector Count (Total)Gauge
ATX connector 20+4 pin (620mm)1118AWG
4+4 pin EPS12V (650mm)1118AWG
6+2 pin PCIe (650mm)2218AWG
SATA (500mm+150mm+150mm+150mm)2818AWG
Four-pin Molex (500mm+150mm+150mm+150mm)1418AWG

Cable length is ample and the connector count is sufficient, given this PSU's capacity. With two PCIe connectors, you're free to pick from a bevy of high-end graphics options. We also don't expect a PSU in this category to have more than one EPS connector.

Eight SATA connectors will cover the needs of most users, while Bitfenix chose not to include even a single Berg (FDD) connector. We don't think an adapter would affect the BWG550M's price, so it'd be nice to see Bitfenix add one to this PSU's bundle since some components still use that particular connector.

Power Distribution

Swipe to scroll horizontally
12V1ATX, Peripheral, SATA

Power distribution is optimal; the EPS connector doesn't share a rail with the PCIe ones. It's worth noting that you can connect the EPS connector to a VGA (PCIe) socket since they're identical. There's no reason to do this, though, unless you want more power from the EPS connector and you use a low-end graphics card with just one PCIe connector.

MORE: Best Power Supplies

MORE: Power Supplies 101

MORE: How We Test Power Supplies

MORE: Picking The Right Power Supply: What You Should Know

MORE: All Power Supply Content

Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

  • turkey3_scratch
    Bitfenix did the right thing pairing with CWT here. This is a great unit!
  • Aris_Mp
    Indeed, its performance was a nice surprise for me as well. It's good to see some new competition in this market.
  • Nuckles_56
    Damn, I wonder what Australian pricing will be like for this unit, as I'd be almost tempted to replace my current PSU with a quieter one like this if it is priced well
  • MarekRMac
    Hi, please give me quick advice: Bitfenix Whisper M 550W or Corsair RM550x ?
  • Aris_Mp
    19083753 said:
    Hi, please give me quick advice: Bitfenix Whisper M 550W or Corsair RM550x ?

    Which ever you can find at a lower price. Performance wise they are very close.

  • jonnyguru
    One noticeable difference between the RMx and the Whisper is that the RMx uses an MCU for the fan controller instead of the standard thermistor/transistor circuit in the BitFenix product.