Cooler Master X Silent Edge Platinum 850W power supply review

Cooler Master, founded in 1992, is a well-known manufacturer specializing in high-performance PC hardware components and cooling solutions. The company offers a wide array of products, including PC cases, power supply units (PSUs), cooling systems, and peripherals, catering to both mainstream users and high-end enthusiasts. In the power supply segment, Cooler Master has developed several innovative designs, with the X Silent Edge Platinum positioned as a premium, fully fanless power supply aimed at users seeking absolute silence without sacrificing performance.

We examine the X Silent Edge Platinum 850W power supply, a high-end, passively cooled design for those who demand top-tier efficiency and cutting-edge engineering. Can this high-end, fanless powerhouse go toe-to-toe with some of the best power supplies we’ve tested? Cooler Master claims full in-house development for this unit, making it a unique addition to the market. With its massive heatsink-based chassis, high-quality components, and an ultra-long 15-year warranty, the X Silent Edge Platinum is designed to deliver stable and reliable power in absolute silence. However, its premium pricing and large footprint raise questions about its practical appeal.

Specifications and Design

In the Box

Cooler Master supplies the X Silent Edge Platinum in a tough and large cardboard box with an extremely simple all-black theme. Inside, the PSU is well-protected by thick foam inserts and wrapped in a nylon cover to prevent any damage during shipping.

The included accessories are relatively minimal for a power supply of such a tier. Cooler Master provides the necessary mounting screws, an AC power cable, a few cable ties, and two cable straps. The bundle basically just covers the essentials.

The X Silent Edge Platinum features all-black, individually sleeved cables with black connectors, offering a clean and sophisticated look. The cables are notably soft and flexible, making cable routing easier. The 12V-2×6 PCIe cable includes a 90-degree connector, which Cooler Master claims enhances reliability due to its improved contact mechanism and thickness. The number of connectors provided is very good considering the unit’s power output.

External Appearance

The Cooler Master X Silent Edge Platinum is a significantly larger power supply, measuring 180 mm in length. Its extended footprint means that compatibility with compact ATX cases should be carefully verified before installation. It is uniquely designed, with a chassis that is part heatsink, part vented enclosure, and its sheer size and weight make it stand out from typical ATX power supplies.

The unit features a satin black finish with chamfered edges for a refined aesthetic. The left side of the chassis houses the label displaying the power supply’s electrical specifications and certifications, while the right side resembles a heatsink. A substantial portion of the unit’s bottom, rear, and sides features ventilation cutouts to assist in passive cooling, while the top consists of a massive solid aluminum heatsink that acts as the main cooling mechanism for the unit’s secondary inversion circuitry.

At the rear, the X Silent Edge includes the standard AC input socket and a standard power switch. The front panel hosts the modular cable connectors, with a subtle legend printed around them for guidance. There is also a USB port and cable, which can be used to monitor some of the unit’s basic figures (temperature, power output) via Cooler Master’s MasterCTLR software.

Internal Design

Unlike most power supplies that rely on active airflow, the Cooler Master X Silent Edge Platinum is designed for entirely passive operation, utilizing massive heatsink configurations and even heatpipe-assisted thermal dissipation. The internal layout is optimized for high thermal efficiency, with major heat-generating components connected to the aluminum chassis for effective passive cooling. The heatsinks of this unit are massive and even the transformer has one attached to it.

Cooler Master claims that this power supply is entirely developed in-house, and we could not recognize its OEM. The input filtering stage is robust, featuring four Y capacitors, two X capacitors, and two filtering inductors. Most of these components are directly integrated behind the AC receptacle.

The input rectification circuitry utilizes a bridgeless approach, with four MOSFETs replacing traditional rectifier bridges. The Active Power Factor Correction (APFC) stage employs two Infineon CoolSiC MOSFETs and a single diode for power factor correction, while an encased inductor and two EPCOS 560 µF capacitors handle passive energy storage. The capacitors are placed within a protective cocoon comprising thick heat shrink and resin, possibly to enhance thermal insulation.

The primary conversion stage employs a full-bridge LLC topology, consisting of four high-quality Infineon 60R070CFD7 MOSFETs. These MOSFETs are known for their efficiency and thermal performance, making them well-suited for a fanless power supply.

The X Silent Edge Platinum features a premium selection of capacitors. The secondary side consists almost entirely of solid-state polymer capacitors supplied by Nippon Chemi-Con, with only two small Rubycon electrolytic capacitors present.

Cold Test Results

Cold Test Results (25°C Ambient)

For testing PSUs, we use 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.

During cold testing, the Cooler Master X Silent Edge Platinum delivered an average nominal load efficiency of 90.8% at 115 VAC and 92.4% at 230 VAC, meeting the 80Plus Platinum certification requirements. At 115 VAC, the unit qualifies for CLEAResult Platinum certification, while at 230 VAC it narrowly misses the 94% efficiency threshold at 50% load. Notably, the unit peaks at 94.1% efficiency at 60% load, which highlights the weaknesses of the CLEAResult efficiency certifications. Cybenetics, whose certification is largely based on average efficiency, awarded the X Silent Edge Platinum a Platinum certification across all input voltages, as well as their best noise certification—a natural outcome of its completely fanless design. The thermal performance is consistently linear throughout the test range, with internal temperatures maintained within safe limits despite the absence of active cooling.

Hot Test Results

Hot Test Results (~45°C Ambient)

During hot testing, the Cooler Master X Silent Edge Platinum achieved an average nominal load efficiency of approximately 90.0% at 115 VAC and 91.5% at 230 VAC. This represents a modest decrease of roughly 0.8 to 0.9 percentage points compared to room temperature. Such a slight reduction under elevated ambient temperatures is expected from any typical PC power supply. The efficiency drop under heavy loads indicates some degree of thermal stress on the active components, but the effect is small, even though we are testing the unit above its rated temperature threshold for maximum power output. Internal temperatures are relatively high but do not reach dangerous levels. The unit’s completely fanless operation guarantees absolute silence, even under adverse conditions, setting it in a different league from active cooling designs.

PSU Quality and Bottom Line

Power Supply Quality

The Cooler Master X Silent Edge Platinum power supply demonstrated good electrical performance, with voltage regulation maintained at approximately 1.2% on the 12V rail, 1.6% on the 5V rail, and 1.8% on the 3.3V rail. Ripple suppression was commendable, with maximum ripple levels of 40 mV on the 12V rail and 20 mV on both the 5V and 3.3V rails. Although these figures are very good for a modern PC power supply, they do not stand out, which could spell trouble for the X Silent Edge, considering its highly premium character.

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). All protection mechanisms were activated and functioned correctly during testing.

The OCP thresholds were set at 120% for the 3.3V rail, 122% for the 5V rail, and 110% for the 12V rail, while the Over Power Protection (OPP) activated at 112% under hot conditions. These protection levels are very sharp and low for an ATX 3.1 unit, but we feel they are well-calibrated to ensure reliable operation in a fully fanless design.

Bottom Line

The Cooler Master X Silent Edge Platinum 850W power supply represents a bold leap in high-end power supply design, marrying form with function through its innovative, fanless architecture. Externally, the unit’s massive 180 mm length and substantial weight immediately signal its unique and premium nature. Cooler Master carefully designed this unit’s exterior to be very appealing but not extravagant. Designed for enthusiasts who demand absolute silence in their systems, this power supply is targeted at users building high-performance rigs where noise reduction is as critical as power delivery.

Internally, the X Silent Edge Platinum is a showcase of advanced thermal engineering. Cooler Master’s in-house development has resulted in a layout that leverages massive heatsink configurations and heatpipe-assisted thermal dissipation to manage heat without any active cooling and under virtually any environmental conditions. All major active components are top-quality Infineon MOSFETs, ensuring stable performance and top efficiency. Typically, such a design should reach Titanium efficiency levels, but the X Silent Edge is tuned towards sustaining its efficiency very high across the entire load spectrum. The use of premium polymer capacitors from Nippon Chemi-Con, supplemented by a minimal number of Rubycon electrolytic capacitors, further underscores the unit’s dedication to long-term durability and high-end performance. This unit is covered by a 15-year long manufacturer’s warranty – the longest we have ever seen to this date.

Performance-wise, the X Silent Edge Platinum does not disappoint. Cold testing at a 25°C ambient temperature revealed nominal load efficiencies of 90.8% at 115 VAC and 92.4% at 230 VAC, with efficiency peaking at an impressive 94.1% at 60% load. These results meet the 80Plus Platinum certification requirements at 115 VAC, while the unit narrowly misses the threshold at 230 VAC under specific load conditions. Under hotter conditions (~45°C ambient), the efficiency drop is very well within acceptable margins. The power quality of the unit is great but, unfortunately, it does not really stand out by today’s standards, which we feel that it should be considering its price tag.

In summary, the Cooler Master X Silent Edge Platinum 850W is a notable achievement in silent power delivery, crafted for those who value both performance and absolute quiet operation. While its innovative passive cooling design and meticulous internal architecture justify its premium positioning, the extremely steep $550 price tag restricts its appeal to a niche high-end market. For users building ultra-quiet, high-performance systems, this power supply offers exceptional quality and reliability. However, budget-conscious buyers or those with space-constrained cases might find its cost and dimensions prohibitive. Overall, the unit stands as a testament to cutting-edge engineering, albeit with trade-offs that warrant very careful consideration.

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