Bitfenix Formula Gold 750W PSU Review

1. Introduction2. Bundle & Cables3. External4. Internal5. Testing Methodology & Results6. Closing Thoughts7. View All Pages

A new power supply from Bitfenix recently graced our labs – the Formula Gold 750W. This is an 80 Plus Gold, non modular unit targeting the mass enthusiast audience. Bitfenix say they are using high grade components inside to deliver good electrical performance with low acoustic noise. They are releasing four models in this range – 450W, 550W, 650W and 750W. We look at the highest power model in the range today.

Bitfenix have been working closely with CWT in the design of these particular units and the end product involves a custom PCB design specifically for Bitfenix. The platform is LLC/DC-DC but it is different to the Whisper M series – which is modular.

Bitfenix are attempting to achieve a competitive price point for this power supply and we have heard from Overclockers UK that pricing will be set at £82.99 inc vat. Based on today's pricing that is about £17 less than Bitfenix own Whisper M Series 750W (also 80 Plus Gold) available here at £99.95 inc vat.

Technical Details:

• Dimensions: 150 x 86 x 140 mm (W x H x D)
• Fans: 120 mm (FDB bearings, automatic control with particularly low RPM)
• Colour: Black (PSU, fan)
• Efficiency: minimum 91/90/88 % at 50/20/100 % load (115 Volt input voltage; efficiency up to 2% higher at the 230V common in Europe), 80 Plus Gold Certification
• Active PFC
• Form Factor: ATX12V 2.4
• Connectors (Modular):
  1x 20+4-Pin ATX12V/EPS12V
  2x 4+4-Pin ATX12V/EPS12V
  4x 6+2-Pin-PCIe
  8x SATA
  4x 4-Pin Molex
• Manufacturer's Guarantee: 5 Years

Review photography handled in house at KitGuru with a Leica S series medium format camera and S series prime lens. Please do not use any of the images within this review without express permission.

Bitfenix artwork is actually pretty good. You get a close up look at the fan grill of the unit which features their weird looking logo in the center. The front of the box highlights the 80 Plus Gold Certification and the 5 year warranty.

The rear of the box shows details of the cabling, the amount of connectors, the dimensions of the power supply along with the specifications and fan speeds under load conditions.

Inside Bitfenix include a regional specific power cable, cable ties, mounting screws and a user manual. The power supply itself is protected inside an egg shell style cardboard box. It rates as adequate protection but not the best we have seen.

The main ATX cable is sleeved – although all the rest are flat ribbon style for ease of routing.

Above, a breakdown of the cabling on the Bitfenix Formula Gold 750W unit. There are four PCIE 6+2 Pin cables to support a variety of dual card Crossfire and SLI system builds.

I actually really like the look of the Bitfenix Formula Gold supply. The paint work is surprisingly good quality and they have opted for simple white accenting which means it will work well in a variety of schemed system builds. It rates well against scratching although finger prints will show up.

The large fan is hidden behind a black metal shroud with the Bitfenix logo getting pride of place in the centre.

One side of the power supply is home to the power connector and switch along with a vented panel to help ensure there is good airflow inside.

As this is not a modular power supply there is no connector panel on the other side just a set of hardwired cables which emerge from the chassis. We can see a plastic grommet in place to help stop fraying from the cables against the metal chassis.

Bitfenix Formula Gold 750W
DC Output	+3.3V	+5V	+12V MBPH	+12V CPU	+12V VGA1	+12V VGA2	-12V	+5Vsb
Max Output	22A	22A	25A	25A	35A	35A	0.5A	2.5A
Total Power	120W		750W				6W	12.5W
	750W

Both +3.3V and +5V rails can deliver 22A and the +12V rails deliver 25A, 25A, 35A and 35A accordingly for a total of 750W.

Bitfenix are using a Martech 120mm fan with the moniker DF1202512SEMN – rated 12VDC, 0.37A and 4.44W.  We can see the plastic cover over part of the power supply to direct air onto specific parts of the power supply.

While there is very little information about this fan online, we found out that it is an HDB fan – a sealed sleeve bearing which means the lubricant will last much longer than a regular sleeve bearing.

Below - a High Resolution Gallery of the internal layout of the Power Supply

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The OEM for this specific unit is CWT and they are using a custom PCB created in conjunction with Bitfenix themselves. We have been told that this design is unique to Bitfenix and will not be shared by other CWT partners. The Primary side is a half bridge design with an LLC resonant converter. The secondary side is synchronous rectification to generate the +12V. The Minor rails are dealt with by some VRMS.

The transient filter starts at the AC receptacle with an X cap and two Y caps. Power cabling is wrapped around a ferrite ring to suppress EMI. The transient filter continues to the main PCB consisting of another X cap, two more Y caps, two CM chokes and a MOV.

The build quality is high and the soldering quality is good. There is plenty of airflow from above across the heatsinks to help keep everything cool.

I was pleased to see the company adopting high grade 105c rated Japanese capacitors. The primary capacitor is from Nichicon who are based in Kyoto, Japan. It is rated 680uF 400v. Secondary side capacitors are also Japanese.

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. Due to public requests we have changed our temperature settings recently – previously we rated with ambient temperatures at 25C, we have increased ambient temperatures by 10c (to 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

DC Output Load Regulation
Combined DC Load	+3.3V		+5V		+12V		+5VSB		-12V
	A	V	A	V	A	V	A	V	A	V
75W	0.95	3.35	0.91	5.01	5.11	12.07	0.50	5.03	0.20	-12.05
150W	1.65	3.35	1.68	5.01	10.61	12.05	1.00	5.03	0.20	-12.05
375W	3.00	3.35	3.05	5.01	28.11	12.03	1.50	5.02	0.30	-12.04
565W	4.02	3.34	4.05	5.00	42.95	12.01	2.00	5.02	0.30	-12.05
750W	4.90	3.33	5.25	4.99	57.50	12.00	2.50	5.01	0.50	-12.04

Load regulation is good holding within 1.5%.

Bitfenix Formula Gold 750W	Maximum Load
	842W

We managed to reach around 842W before the unit would shut down gracefully, after the protection kicked in. This is around 90 watts more than the rated output, quite a good result.

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
734W	1.0	3.37	1.0	5.02	60.0	11.93	0.2	-12.06	0.50	5.03
154W	15.0	3.30	15.0	4.98	2.0	12.10	0.2	-12.04	0.50	5.01

The unit passes our Cross Load testing although there is noticeable variance on the +12V rail when hit with 60 amps.

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
75W	5	10	15	10
150W	10	15	20	10
375W	10	15	25	10
565W	10	15	30	15
750W	15	20	35	15

Ripple results are good with both +3.3V and +5V output holding at 15mV and 20mV respectively at full load. The +12V output holds at 35mV at full load.

Efficiency (%)
75W	87.42
150W	91.31
375W	92.21
565W	91.36
750W	90.62

Power efficiency rates as very good indeed, hitting a peak over 92% at 50% load. At full load it drops to 90.6%, another stellar result.

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)
75W	<28.0
150W	<28.0
375W	<28.0
565W	32.6
750W	34.7

The large fan in the Formula Gold power supply maintains a low noise curve throughout the range of load. It is only at close to full load that the fan makes its presence known. Stellar results.

Temperature (c)
	Intake	Exhaust
75W	36	40
150W	38	42
375W	39	46
565W	45	53
750W	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
842W	89.66

For those interested, we measured efficiency when stressing the unit to breaking point. 89.7 percent efficiency at 832W … hardly practical, but interesting regardless.

The Bitfenix Formula Gold is a solid power supply and the OEM design from CWT is technically as good as you are going to get at this price. The Whisper range of supplies have apparently been selling well to the higher end enthusiast user so it makes sense for Bitfenix to release a more cost effective range of supplies for a wider audience.

I was pleasantly surprised by how quiet the Formula Gold was in operation. Its true that under full load conditions you will hear the fan but that is not a likely situation in most cases. If you need a constant 750 watts at the socket you need to be aiming for a larger capacity power supply.

The pricing in the United Kingdom is fairly competitive – its available on pre-order right now from Overclockers UK for £82.99 inc vat HERE. This makes it around £17 less expensive than the Bitfenix Whisper M Series 750W which is available for £100 HERE.

In the United Kingdom there are competitor products available, but they are louder and more expensive and if you can live with the lack of modular cabling, then the Bitfenix Formula Gold 750W is hard to beat at the price. Internally we are always pleased to see 105c rated Japanese Capacitors – so kudos to Bitfenix for not taking the cheaper route in the Chinese market.

For £82, and considering the performance and lack of noise at high output – the Formula Gold 750W supply should be right at the top of your shortlist. It is a quality unit that doesn't cost the earth. The five year guarantee isn't groundbreaking, but at the price, it should offer some peace of mind.

Buy from Overclockers UK for £82.99 inc vat HERE.

Pros:

• Competitive pricing.
• Technically solid.
• Very low noise levels.
• Compact.
• 105c Japanese Capacitors.
• Tight Load Regulation.
• delivered almost 850 watts.
• Good Ripple Suppresion.

Cons:

• Not modular.
• only a 5 year warranty.

KitGuru says: This is a great power supply at a very competitive price point and should be right at the top of your shortlist.

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