BitFenix is a company that became known for their unique, yet cost-effective computer case designs. The company was initially focused solely on PC cases, but quickly expanded their products portfolio to include other related products, such as case modding items, fans, and power supply units. A little over a year ago we reviewed two of their first PSUs, the BitFenix Whisper M 450W & 850W units, which we found to be both capable and competitively priced.

For today's review  we are taking a look at the latest addition to the company's PSUs lineup, the Formula Gold 650W PSU. As its name suggests, the Formula Gold series comes with an 80Plus Gold efficiency certification, with a long list of impressive features and rather bold quality assurance assertions on its marketing sheet. BitFenix claims that it is one of the most cost-effective 80Plus Gold units in the market, though with a retail price of $80 for the 650W version, it faces some aggressive competition amongst other 80Plus Gold designs. Ultimately this is a PSU with both its advantages and shortcomings, as we'll see in this review.

Packaging and Bundle

BitFenix supplies the Formula Gold 650W PSU in a typical cardboard box, with thick walls that offer ample shipping protection. Inside the box, we found the unit well-protected in polyethylene foam pieces. The artwork is mostly black, with abstract geometric shapes forming a partial triangular mesh and a close-up picture of the PSU itself. Abundant information regarding the unit's main features and performance is printed on the sides and rear of the box, in multiple languages.

In an effort to keep the cost as low as possible, the company reduced the bundle to the absolute essentials. We only found the necessary AC power cable, four black mounting screws, a few zip ties, and a basic manual inside the box. There are no other items or cables, as this particular PSU has all of its cables hardwired to the chassis, none are removable.

External Appearance

The 650W version of the BitFenix Formula Gold PSU is built inside an ATX-compliant chassis that is just 140 mm deep. Although none of the cables are modular, the designer tried to make the unit aesthetically unit via simple interventions. The fan cutout is rectangular instead of circular, with a finger guard to match. A round metallic badge with the company logo lays enclosed into the bars of the fan's guard, right above the engine. A satin black paint covers the chassis that is very well applied but also exceptionally prone to fingermarks. Decorative side stickers cover both the left and right side of the PSU. A large sticker with the electrical specifications and certifications of the PSU can be seen at the top side of the chassis.

The front and rear sides of the unit are textbook. A simple AC cable receptacle and an on/off switch can be seen at the perforated rear side of the PSU, with a large dead area below them that would normally be home to a company logo badge, but BitFenix decided to minimize visual interferences (and lower the manufacturing cost a bit). The front is entirely plain, with only a single opening where all of the cables are coming out from.

All of the unit's cables come out from a single port. The wires and connectors are all black, with flat, ribbon-like wires without any external covering for almost every cable. The only exception is the thick 24-pin ATX cable, which is made of simple wires that are enclosed into black nylon sleeving. A significant part of the 24-pin ATX cable is covered in heat shrink and appears to be curiously thick. That is because the heat shrink is hiding extra filtering capacitors for improved power quality, an approach that definitely helps but also makes the ATX cable very rigid and a nightmare during cable management.

Internal Design

Due to the standard 140 mm long chassis, the largest fan that can fit in the Formula Gold is an 120 mm one. The fan is supplied by MARTECH, a relatively reputable but not very popular Chinese manufacturer. Its part number is DF1202512SEMN and has a rifled sleeve bearing engine. Its maximum speed is about 2000 RPM, which is relatively high for a 120 mm fan and would make the PSU very loud if it were to work near its top speed.

A simple glance inside the Formula Gold reveals a familiar design. I am quite confident that the OEM behind the Formula Gold is Channel Well Technology (CWT), the same company behind the previous BitFenix Whisper M units. The platform of the Formula Gold is wholly different than that of the Whisper M, appearing to be yet another upgrade of the GPN platform that CWT first released many years ago, with many versions in between then and today.

The filtering stage of the Formula Gold begins at the rear of the AC receptacle, where we see two Y capacitors and one X capacitor. Two more Y capacitors and one more X capacitor, as well as two filtering inductors and a surge-suppressing MOV can be seen on the main PCB, summing up to a textbook filtering stage. The large heatsink across the right side of the unit holds the single bridge rectifier, the active components of the APFC stage, and the two MOSFETs of the primary inversion circuit. The APFC stage capacitor is supplied by RubyCon and is rated at 400V/680μF.

The primary inversion circuit is relatively simple, with two MOSFETs forming a half-bridge topology that is supported by an LLC resonant converter. The MOSFETs of the secondary side are on the underside of the PCB, with thin and tall heatsinks attached directly on the main PCB to provide cooling for them. The secondary conversion circuit generates only the 12V line, the 3.3V/5V lines are being derived via tertiary DC-to-DC converters. The secondary side electrolytic capacitors are all supplied by Nippon Chemi-Con, while the polymer capacitors inside the PSU are supplied by Nichicon. The capacitors in the ATX cable are supplied by Nippon Chemi-Con. All of the capacitors of the Formula Gold are supplied by Japanese manufacturers, just like BitFenix says they are.

Cold Test Results

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.

Meanwhile, by request, we're also including 115 VAC results with this PSU review, for our readers in North America and other 115 VAC regions. Modern power supplies work on both systems, however the nature of switching means that they are slightly more efficient with higher voltage inputs. So this lets us show where their efficiency stands on a 115 VAC system.

The BitFenix Formula Gold 650W meets the 80Plus Gold certification standards when powered from either a 230 VAC or 115 VAC source. With an input voltage of 230 VAC, the peak efficiency is 92.2% at 50% load, while the average nominal load (20%-100%) average efficiency is 90.9%. The conversion efficiency drops when the unit is powered by an 115V/60Hz source, peaking at 90.4% at 50% load and delivering an average efficiency of 89% across the nominal load range. However, the efficiency drop is not uniform. At low loads the difference is insignificant but it widens as we load increases, up to a maximum of 2.6% at maximum load.

BitFenix kept things simple and did not implement a semi-fanless thermal control scheme but the thermal control parameters are very well programmed. The fan is staying indiscernibly quiet with a load up to about 400 Watts, providing adequate cooling with very low noise levels. As the load increases beyond 400 Watts, the fan's speed slope increases, decreasing the rate at which the internal temperature rises. The maximum noise level coming from the Formula Gold 650W unit at room temperature is 40.6 dB(A) at maximum load, meaning that is clearly audible but most users would not find that uncomfortable in an office/gaming environment.

Hot Test Results

In the following tables we can see that the BitFenix Formula Gold 650W delivers fair power quality. The maximum voltage ripple on the 12V line is 34 mV, which may be an unimpressive figure nowadays but it is just 28% of the ATX design guide's recommended 120 mV limit. The filtration on the minor 3.3V/5V lines is a little worse, with the ripple reaching 22 mv (44% of the 50 mV ATX design guide recommended limit). On the contract, voltage regulation on the 3.3V/5V lines is at 0.5%, an exceptional figure, whereas the regulation of the 12V line reaches 1.4%. Keeping in mind the class of the product, these figures are excellent.

Operation in high ambient temperatures affects the performance of the Formula Gold 650W PSU by a measurable, yet reasonable amount. The average nominal load range (20%-100%) efficiency drops by 0.8% regardless of the input voltage, going down to an average of 90.1% (230 VAC) / 88.2% (115 VAC). The efficiency drop is miniscule at lower loads but is more significant at high loads, suggesting that the components of the PSU are getting slightly thermally stressed under these conditions.

A look at our temperature graphs comes to back up our previous assumption, as the internal temperatures of the Formula Gold 650W PSU are quite high for a unit with this kind of power output. The thermal control does make an effort to keep the temperatures within reasonable levels, forcing the fan to spin a lot faster than before. Although the fan reaches uncomfortable noise levels with a load of just 300 Watts, it is unable to halt the ever-rising temperature. The Formula Gold 650W PSU barely works at maximum load under these conditions, as the temperatures are right before the point where its thermal protection would shutdown the unit.

Unlike operation in room temperature, the thermal control circuit will continuously increase the fan's speed under these conditions. The increase rate is almost linear, meaning that every increase on the unit's load will also increase the unit's noise output. The noise coming from the PSU's fan reached uncomfortable figures with a load of 300 Watts, with the sound pressure level going above 50 dB(A) at maximum load.

Conclusion

It is obvious that BitFenix has positioned the Formula Gold series as a cost-effective power supply for users who are after high reliability and performance but are not particularly concerned about the aesthetics of their system. The Formula Gold is the fruit of their continuous cooperation with Channel Well Technology (CWT), an OEM known for their excellent mid-range designs. To that end the 650-Watt version that we reviewed today offers ample power for any gaming system with a single graphics card, exactly the market BitFenix is going after.

In terms of performance, the Formula Gold may not be breaking any records but it does offer above-average overall performance. Electrical performance is its strong suit, with excellent voltage regulation and great filtering. It also is capable of honoring its 80Plus Gold certification regardless of the input voltage. The Formula Gold also offers very good acoustics performance under normal operating conditions, with the unit's fan staying almost entirely silent most of the time. Only thermal performance is mediocre, which is due to the far too simplistic heatsinks, but it will not become an issue unless the Formula Gold is operating in a very hot environment and under a continuous heavy load.

Aesthetics were partially sacrificed to reduce the retail price of the product. The biggest omission is the lack of even partial modularity, as all of the cables are hardwired inside the PSU. The exclusion of an entire secondary PCB and the several connectors that a modular design would need have significantly reduces the PSU's manufacturing cost, as both the bill of materials and the process time is reduced. Nevertheless, BitFenix did not forgo aesthetics entirely, with the designer applying simple but significant touches, such as the unique rectangular fan opening and the all-black design.

The Formula Gold is made with very high-quality parts and, true to their word, BitFenix is sourcing all capacitors from Japanese manufacturers. Our only complaint lies with the relatively small heatsinks that, as we have seen in the previous pages of this review, can definitely impact the thermal performance of the unit. Slightly better heatsinks would have increased this unit's thermal performance significantly, though admittedly it would also increase its manufacturing cost.

Speaking of cost, next to its solid electrical performance, cost is the other angle BitFenix is playing with this power supply, touting that it can provide outstanding performance at an unparalleled price tag. However a quick market search finds that there are several similar 80Plus Gold units that can rival the price tag of the Formula Gold. Some are even of modular design and are selling for roughly the same price or even less. This, along with the limited availability of the PSU, will certainly be a bit of a headache for BitFenix. The Formula Gold certainly is a worthy product that will leave no mainstream user disappointed but, in terms of value, it currently does not really stand out of the crowd.