In the retail PC PSU space, most of the focus on new standards and their capabilities in the past couple of years has been on ATX 3.0 and it's quick follow-up successor, ATX 3.1. And while the revised ATX standard is certainly the most important new standard for the rank-and-file PC builder, it's not the only standard that has been released as of late. Intel and its partners have also developed a standard, that in some respects, goes even farther out by dropping some of the legacy aspects of ATX and its increasingly esoteric secondary voltages: ATX12VO.

Short for "ATX 12 Volts Only", ATX12VO is a standard that's been slower to take off as it makes a pretty hard break with backwards compatibility. But with so many motherboard functions running off of 12V (CPUs and GPUs, for a start), the need for a PSU to provide secondary voltages like 3.3V and 5V just aren't what they once were 20 years ago - or even 10. So we've slowly seen PC manufacturers and motherboard makers test the waters, with a handful of designs using the more petite ATX standard.

Meanwhile on the power supply side of things, the outcome has been a bit more interesting, if messy. While ATX12VO motherboards need matching PSUs, there's nothing to say that such a PSU can only be ATX12VO. To reference an ancient meme, the thought at some PSU manufacturers has been "why not both?", leading to high-end PSUs that can bridge the compatibility gap by offering both ATX 3.1 and ATX12VO compatibility.

The first example of such a PSU to make it in our labs is Enermax's new PlatiGemini 1200W PSU. Designed to be the Swiss knife of modern top-tier PCs, Enermax's PSU offers support for both ATX 3.1 and ATX12VO - ensuring it can power virtually any PC - while driving both modes with a sizeable 1200W design that can pretty much power virtually any desktop PC one can hope to build today. Plus, with features like fully modular cables with per-wire sleeving, a dynamic hybrid fan control for optimal cooling, and advanced power topologies, the PlatiGemini 1200W aims to deliver both reliability and performance on top of its multi-mode compatibility. The end result is a very interesting (if premium) product that can do it all.

Packaging and Bundle

The Enermax PlatiGemini 1200W ATX 3.1 PSU comes in straightforward yet efficient packaging. The outer box, a simple cardboard design, is visually enhanced with a decorative ribbon. The PSU itself is well-protected during shipping by a nylon bag and dense packaging foam, ensuring it arrives in perfect condition.

The bundle includes more than just the essential mounting screws and AC power cable - a manual, a jump-start adapter, and cable combs are also included.

This PSU features all-black cables, including connectors and wires, with individually sleeved wires, providing the PlatiGemini unit with a premium aesthetic factor. Enermax also includes an ATX12VO connector, which is one of the highlights of this series. Strangely, for the massive 1.2 kW output of the unit, the total number of connectors is fairly low.

The Enermax PlatiGemini 1200W ATX 3.1 PSU

External Appearance

The Enermax PlatiGemini 1200W ATX 3.1 PSU is housed in a chassis that measures 150 mm in length, slightly longer than the standard ATX dimensions specified by the ATX design guide. This extra length accommodates the 135 mm cooling fan, ensuring better cooling performance and fitting into all ATX-compliant tower PC cases.

This PSU boasts a sleek and subtle design, highlighted by its matte textured black finish. The unit eschews unnecessary decorations, featuring prominent chrome logos on the sides for a clean look instead. The top side is covered with a sticker detailing the electrical specifications and certifications.

The front side of the unit includes the standard on/off switch and AC cable receptacle, as well as a switch for the Dust Free (D.F.) function, which reverses the fan direction to blow dust away. The rear hosts the modular cable connectors, organized for easy and error-free connections. While the connectors are not color-coded, they are labeled with a simple, bright white legend next to each connector, aiding in accurate cable management. A white imprint of the company logo can also be found on the rear side, enhancing aesthetics.

Internal Design

The Enermax PlatiGemini 1200W PSU is equipped with a Zeta Group ZFB132512H 135 mm fan, featuring a ball-bearing engine. This type of fan is known for its reliability and durability, making it a common choice for high-quality PSUs. While ball-bearing fans can be slightly louder at higher speeds, they excel in high-temperature environments. The fan in this model can reach a maximum speed of 1800 RPM, a relatively conservative figure, suggesting that Enermax’s engineers have a lot of faith on this unit’s efficiency.

The Enermax PlatiGemini 1200W ATX 3.1 PSU is produced by Shenzhen Rui Sheng Yuan, an OEM with extensive experience in the power supply industry, despite past reliability issues between 2015-2017. Their long history in power electronics enables them to produce mid to high power output PC power supplies. They seem to be behind at least several of Enermax’s latest units.

This platform is based on well-established topologies, designed with reliability in mind. The input stage features a basic transient filter, consisting of two Y capacitors, one X capacitor, and two filtering inductors. The Active Power Factor Correction (APFC) setup includes two rectifying bridges attached to a dedicated heatsink, supplemented by four APFC MOSFETs (50R140CP), three diodes, a large encased filtering inductor, and two Rubycon 560 μF capacitors. The active components are sandwiched between two plates that also serve as basic heatsinks.

In its primary inversion stage, the Enermax PlatiGemini utilizes a full-bridge LLC topology with high-quality Infineon 50R140CP MOSFETs. Uniquely, the primary side transistors are on a vertical PCB without any heatsink attached directly on them. The secondary stage features eight Infineon 014N04LS MOSFETs, using synchronous rectification for the primary 12V line, with 3.3V and 5V rails generated by DC-to-DC circuits on a vertical daughterboard. There is an extra rectification circuitry to generate the 5VSB and 12VSB voltages, as required for the ATX12VO compliance. The secondary side capacitors are a mix of top-tier Japanese products from Rubycon, Nichicon, and Nippon Chemi-Con, ensuring reliability and performance.

Cold Test Results (~25°C Ambient Temperature)

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.

The Enermax PlatiGemini 1200W PSU comfortably meets the standards of the 80Plus Platinum certification, even though input voltage significantly impacts efficiency. When tested with a 115 VAC input, this PSU achieves an average nominal load efficiency of 91.0% across its operational range from 20% to 100% of its capacity, which rises to 93.2% when operated with a 230 VAC input. The efficiency of the unit peaks at roughly 40% of the unit’s capacity. The efficiency under low loads is quite good as well.

The Enermax PlatiGemini 1200W PSU incorporates a hybrid fan mode, keeping the fan off during low-load conditions to ensure quiet operation. The fan begins to operate only when necessary, which during our testing occurred at loads above 500 Watts, slightly sooner than the unit’s official specifications indicate. The company claim of Zero-RPM up to 60% load is possibly achievable only under ideal laboratory conditions. At typical room temperatures, this allows the PSU to run quietly for most low-to-moderate usage scenarios. As the load surpasses 500 Watts, the fan gradually increases its speed to manage the rising thermal output effectively but never reaches its maximum speed under these operating conditions.

Hot Test Results (~45°C Ambient Temperature)

During hot testing, the Enermax PlatiGemini 1200W PSU demonstrates a slight decrease in efficiency under heavy loads, with recorded figures of 90.4% at 115 VAC and 92.5% at 230 VAC, compared to 91.0% and 93.2% during cold testing. This reduction is moderate and occurs almost linearly across the entire load range. Despite the efficiency drop, there are no signs of thermal stress, even at maximum load. The PSU is rated to perform efficiently at ambient temperatures up to 50°C and it does so seamlessly.

Under hot testing conditions, the Enermax PlatiGemini 1200W PSU's fan activates promptly and accelerates more quickly compared to cooler environments, increasing almost linearly with the load. As the PSU nears 75% capacity, the fan reaches its maximum speed. This strategy keeps noise levels acceptable up to around 50% load capacity, which corresponds to the hefty output of 600 Watts. As the load surpasses this threshold, the fan noise becomes noticeably louder, making the PSU audibly prominent and clearly prioritizing reliability over quiet operation.

Enermax PlatiGemini 1200W PSU displays a very well-balanced cooling scheme, balancing acoustics with thermal performance. The internal temperatures of the unit as kept consistently low, yet without an overaggressive cooling fan profile that would result to premature high sound pressure levels. At loads above 1 kW, the fan has already reached its maximum speed and internal temperatures will rise a bit more sharply, yet they remain relatively low for a unit with this kind of output, especially for one without a heatsink cooling its primary inversion circuitry.

Power Supply Quality

The electrical performance of the Enermax PlatiGemini 1200W PSU is excellent for its class, demonstrating strong voltage regulation across all outputs. The 12V rail maintains a tight regulation of just 0.7%, while the 5V and 3.3V lines are also well-regulated at 0.5% and 0.9% respectively. Ripple suppression is similarly impressive, with low values of 36 mV for the 12V line, 26 mV for the 5V line, and 24 mV for the 3.3V line. These figures are not setting any world records but they are impressive, even for the high tier that this unit is being marketed into.

During our thorough assessment, we evaluate the essential protection features of every power supply unit we review, including Over Current Protection (OCP), Over Voltage Protection (OVP), Over Power Protection (OPP), and Short Circuit Protection (SCP). The Enermax PlatiGemini 1200W PSU successfully passed all critical protection tests, confirming its effectiveness in safeguarding both the PSU and connected components. The unit displayed standard OCP settings for the 3.3V and 5V rails, activating at 122% and 126% respectively, which are typical for these specifications. The 12V rail’s OCP activation at 136% is slightly higher, aligning with the latest industry practices where manufacturers adjust protections to meet power excursion guidelines.

Conclusion

The Enermax PlatiGemini 1200W ATX 3.1 PSU stands out as a high-quality power supply unit that caters to the needs of top-tier systems. The unit combines functionality with a visually appealing design that complements any high-end PC build, boasting a sleek and understated design that exudes a premium feel. Its overall build quality is exceptional, featuring top-of-the-line active and passive components from renowned manufacturers such as Infineon, Rubycon, Nichicon, and Nippon Chemi-Con. The PSU is produced by Shenzhen Rui Sheng Yuan, an experienced OEM, and is backed by a substantial 10-year manufacturer’s warranty. However, despite its impressive 1.2 kW output, the unit has fewer connectors than expected, which could be a limiting factor for some users.

Thermally, the PlatiGemini 1200W PSU is well-balanced, managing to stay cool and quiet under typical operating conditions. The hybrid fan mode allows the unit to remain silent at low to moderate loads, with the fan starting only when necessary, which was observed at around 480 to 500 Watts in testing. This design keeps the PSU virtually inaudible for most usage scenarios. At higher loads, the fan ramps up its speed to manage the increased thermal output, maintaining safe operating temperatures even at maximum load. This effective thermal management ensures both acoustic comfort and reliable performance.

In terms of power quality, the PlatiGemini 1200W meets the stringent requirements of the 80Plus Platinum certification, demonstrating excellent efficiency and performance. The unit achieves an average nominal load efficiency of 91.0% at 115 VAC and 93.2% at 230 VAC during cold testing. Even under hot conditions, the efficiency remains commendable, with only a slight drop to 90.4% at 115 VAC and 92.5% at 230 VAC. The PSU also exhibits strong voltage regulation and low ripple values across all outputs, ensuring stable and clean power delivery. However, while the power quality is impressive, we should note that it also does not significantly outshine other top-tier products in the market.

Overall, the Enermax PlatiGemini 1200W ATX 3.1 PSU is priced at a premium $230, a high price but one aligning with other high-end models in the market. Its compliance with ATX 3.1 and ATX12VO standards, combined with a 10-year warranty and exceptional build quality, makes it a solid choice for demanding users, especially for those who dislike frequent upgrades. Although the limited number of connectors might be a drawback for some, the PSU’s outstanding performance, efficiency, and thermal management make it a viable option for those looking to build or upgrade a high-performance gaming or workstation PC.