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BitFenix Whisper M Series 850W PSU Review

Rating: 8.0.

It has been a long time since we reviewed a Bitfenix power supply and at the time I walked away feeling less than impressed with the overall quality and performance of the unit. Today we analyse the relatively new BitFenix Whisper Series 850 watt supply, a pure modular unit with 80 Plus Gold Certification.

These units are supplied by OEM partner Channel Well Technology (CWT) – a company who have made many high grade power supplies for companies such as Corsair. This Whisper range of power supplies is offered in various capacities ranging from 450W to 850W. Overclockers UK stock them all, and you can see them over HERE.

Bitfenix also supply a reassuring 7 year warranty with this product range.

Bitfenix Whisper 850W Key Features

  • Guaranteed Continuous power delivery with 24 Hour/7 Day operation.
  • Japanese Solid Capacitor Design.
  • LLC resonant topology brings lower power losses and boosts higher efficiency during AC-DC voltage switching.
  • PF value up to 0.99.
  • Up to 92% efficiency @ Typical loading.
  • Advance voltage switching circuit from +12V to minor rail to provide the best stability and output quality.
  • Compatible with Intel Haswell C6/C7 Sleep States.
  • 135mm silence-optimized and long-life Fluid Dynamic Bearing fan.
  • Intelligent Fan Control curve defined.
  • 18AWG Long output DC cable, 650mm for CPU & PCI-E 2.0.
  • 100% Japanese Capacitor used throughout.
  • Over Current Protection (OCP), Over Voltage Protection (OVP), Under Voltage Protection (UVP), Over Power Protection (OPP), Short Circuit Protection (SCP), Over Temperature Protection (OTP), No Load Operation (NLO), Surge & Inrush Protection (SIP).
  • 6 x 6+2pin PCI-E 2.0 connectors for multi-GPU Support.
  • Complies with the latest European Environment Regulation.
  • 7 Year Warranty with BitFenix 24/7 customer service support and solid RMA service.

Review photography handled in house at KitGuru with a Leica S series medium format camera and S series prime lens.

The front of the box is predominately black with a high resolution photograph of the power supply on the right side. A 80 Plus Gold certification logo can be seen top right.

The rear of the box focuses on some of the technical aspects including fan speeds/noise levels, the modular connector panel and a diagram of the cabling.

The box includes a user manual and a little felt bag containing all the modular cables. The box also contains some cable ties, a regional specific power cable and mounting screws (shown in the picture below).

The quality of the modular cabling is high – they are all flat ribbon style, with only the main ATX cable being sleeved.

Connectors

  • 1x 20+4-Pin ATX12V/EPS12V
  • 2x 4+4-Pin ATX12V/EPS12V
  • 6x 6+2-Pin-PCIe
  • 12x SATA
  • 4x 4-Pin-Molex

The BitFenix Whisper M Series 850W power supply is finished in black paint with yellow stickers on the side panels highlighting the product name and branding. Its not the most attractively finished power supply but I wouldn't class it as ugly either. The power supply measures 150 mm (W) x 86 mm (H) x 160 mm (D) and weighs 1.6kg.

The large fan is hidden behind a grill with the Bitfenix logo taking pride of place in the center.

The modular panel is located on one side of the chassis. It is clearly labelled and won't cause any issues during the build phase.

The other side of the power supply is home to the honeycomb cooling vent, power connector and power switch.

Both side panels have ‘Whisper Series' stickers in place.

BitFenix Whisper M Series 850W Power Supply
DC Output
+3.3V
+5V
+12V MBPH +12V CPU +12V VGA1 +12V VGA2
-12V
+5Vsb
Max Output
22A
22A
25A 25A 40A 40A
0.5A
2.5A
Total Power 120W 850W 6W 12.5W
850W

There are four +12V rails and two them are rated lower, at 25A. The +12V rails that handle the six PCIe connector have the higher OCP trigger point.

The first +12V rail is designed to handle the 24 pin ATX cable and MOLEX/SATA connectors. The second +12V rail supports the first EPS connector. The remaining two +12V rails support all PCIE cables.

The fan inside is a 135mm hydro dynamic bearing model by Martech (model number DF1352512SEHN). It is a 12V DC, 0.60A, 7.20W model. The fan is always active as this power supply does not incorporate a semi passive mode.

Below a GALLERY showing the internal design of the BitFenix Whisper M Series 850W

The CWT ‘GPU' design is pretty clean overall with good soldering throughout. The primary side of the supply adopts a half bridge topology with an LLC resonant converter. On the secondary side there is a couple of DC-DC converters for generation of the minor rails. Both of these converters are mounted on a vertical board.

Transient filtering starts at the AC receptacle with an X cap and two Y caps. Power cables are wound around a ferrite ring to help reduce EMI. The secondary stage of transient filtering is on the main PCB and it consists of an X cap, two Y caps, two CM chokes and an MOV.

The primary capacitor is a high grade 105C rated Japanese model by Nippon Chemi Con, from their KMR series to be specific. It is rated 400v 680uF. All electrolytic capacitors are rated 105c, which is good to see.

Correctly testing power supplies is a complex procedure and KitGuru have configured a test bench which can deliver up to a 2,000 watt DC load. We run at 35c in our environment to greater reflect warmer internal chassis conditions.

We use combinations of the following hardware:
• SunMoon SM-268
• CSI3710A Programmable DC load (+3.3V and +5V outputs)
• CSI3711A Programmable DC load (+12V1, +12V2, +12V3, and +12V4)
• Extech Power Analyzer
• Extech MultiMaster MM570 digital multimeter
• Extech digital sound level meter
• Digital oscilloscope (20M S/s with 12 Bit ADC)
• Variable Autotransformer, 1.4 KVA

We test in a single +12V configuration.

DC Output Load Regulation

Combined

DC Load

+3.3V
+5V
+12V
+5VSB
-12V
A
V
A
V
A
V
A
V
A V
85W
0.87
3.37
0.88
5.07
6.05
12.00
0.50
5.00
0.20 -12.03
170W
1.61
3.35
1.64
5.05
12.40
12.00
1.00
5.01
0.20 -12.02
425W
3.18
3.33
3.15
5.02
32.40
11.98
1.50
5.01
0.20 -12.03
638W 4.00 3.30 4.04 4.98 48.94 11.95 2.00 5.01 0.30 -12.03
850W
5.00
3.34
5.20
5.05
65.68
11.92
2.50
5.01
0.30 -12.03

Load regulation is superb with all rails exhibiting very minor fluctuation under load.

BitFenix Whisper M Series 850W Maximum Load
875W

We managed to get the power supply to deliver 875W before it would shut down, delivering around 25W more than rated specifications.

Next we want to try Cross Loading. This basically means loads which are not balanced. If a PC for instance needs 500W on the +12V outputs but something like 30W via the combined 3.3V and +5V outputs then the voltage regulation can fluctuate badly.

Cross Load Testing +3.3V +5V +12V -12V +5VSB
A V A V A V A V A V
760W 1.0 3.37 1.0 5.07 60.0 11.93 0.2 -12.03 0.50 5.01
165W 15.0 3.30 18.0 4.98 2.0 12.02 0.2 -12.02 0.50 5.00

The power supply exhibited some fluctuation dealing with our intensive Cross Loading test. It was tasked with 60A on the +12V rail and it held at 11.93V. The other rails delivered excellent results also.

We then used an oscilloscope to measure AC ripple and noise present on the DC outputs. We set the oscilloscope time base to check for AC ripple at both high and low ends of the spectrum.

ATX12V V2.2 specification for DC output ripple and noise is defined in the ATX 12V power supply design guide.

ATX12V Ver 2.2 Noise/Ripple Tolerance
Output
Ripple (mV p-p)
+3.3V
50
+5V
50
+12V1
120
+12V2
120
-12V
120
+5VSB
50

Obviously when measuring AC noise and ripple on the DC outputs the cleaner (less recorded) means we have a better end result. We measured this AC signal amplitude to see how closely the unit complied with the ATX standard.

AC Ripple (mV p-p)
DC Load +3.3V +5V +12V 5VSB
100W 5 5 5 10
225W 5 5 15 10
450W 5 5 15 15
675W 5 10 20 15
850W 10 10 25 20

Noise suppression results are surprisingly good, hitting 10mV on both the +3.3V and +5V rails. The +12V rail peaks at 25mV under full load conditions. Great results really overall.

Efficiency (%)
100W
90.87
225W
91.45
450W
92.21
675W
91.37
850W 89.88

Efficiency is extremely impressive, peaking at 92 percent at 50 percent load. This drops to around 90 percent at full load.

We take the issue of noise very seriously at KitGuru and this is why we have built a special home brew system as a reference point when we test noise levels of various components. Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

Today to test the power supply we have taken it into our acoustics room environment and have set our Digital Sound Level Noise Decibel Meter Style 2 one meter away from the unit. We have no other fans running so we can effectively measure just the noise from the unit itself.

As this can be a little confusing for people, here are various dBa ratings in with real world situations to help describe the various levels.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refrigerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 Player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

Noise (dBA)
100W
<28.0
225W
<28.0
450W
29.2
675W
35.3
850W 39.1

The large fan spins relatively slowly under most load conditions, it is only in the last 250 watts of rated power output that it spins up and can be audible. It is a little louder than many 850 watt supplies we have tested within the last year, so if you are hyper sensitive to noise then we would recommend you look elsewhere.

Temperature (c)
Intake
Exhaust
100W
37
39
225W
38
42
450W
40
44
675W
45
52
850W
47
58

The high levels of efficiency of this unit help reduce expelled heat. At full load we measured a +11c variable.

Maximum load
Efficiency
875 watts
89.5

At 945 watts, the efficiency level measures 89.5%. Not a practical situation to be running 24/7, but worth noting.

It would be fair to say that I was pleasantly surprised by the overall quality and performance of the BitFenix Whisper M Series 850W power supply. I don't mean that to sound like an attack on Bitfenix, but I have never been a big fan of their power supplies – they have exhibited some issues I was never willing to accept. It was a clever move from them to use the high performance, reasonably priced CWT platform.

Technically the BitFenix Whisper M Series 850W scores well. Ripple suppression is stellar, load regulation is tight and the supply offers a full gamut of protection systems.

The only real downside to this power supply is the somewhat noisy fan when the unit is tasked with higher load demands. Its not horribly intrusive, but if you are sensitive to fan noise and are running a demanding system likely to require more than 600 watts under load then we recommend you look elsewhere. This is not a semi passive design either, but fan noise at lower loads is perfectly acceptable and not annoying at all.

The Whisper Series from Bitfenix is clearly a move in the right direction for the company. If you are building a new gaming system and have around £100 to spend then this BitFenix Whisper M 850W model deserves some serious attention.

You can buy the BitFenix Whisper M Series 850W PSU from Overclockers UK For £105.95 inc vat HERE. There are other, less expensive models in this range, which you can buy over HERE.

Discuss on our Facebook page, over HERE.

Pros:

  • High build quality.
  • Technically very capable.
  • Delivered the full 850 watts without shutting down.
  • Fully modular.
  • quality cabling.
  • 105c Japanese capacitors used.

Cons:

  • Fan gets a little loud under heavier load.

KitGuru says: The BitFenix Whisper M Series 850W is a quality power supply and one that we can recommend at around the £100 mark.

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