
The Cooler Master X Silent Edge Platinum 850 is a fully modular ATX 3.1 power supply with an 850W output, distinguished by its passive cooling system. This fanless design is made possible through a combination of high efficiency at elevated wattages and an advanced array of heat sinks and heat pipes. While this approach completely eliminates fan noise, it also introduces some trade-offs, such as increased weight and limitations on mounting orientation.
Cooler Master introduced this new lineup at Computex 2024, branding the X Silent Edge Platinum 850 as the “industry’s first fanless PSU to achieve 850W”. The unit boasts “totally silent and dustless performance” thanks to its innovative heat pipe technology.
Designed to ATX 3.1 and PCIe 5.1, it includes a 12V-2x6 cable, enabling it to support high-wattage GPUs with up to 600W of power. Specifically designed with the latest GPUs in mind, this power supply demonstrates impressive efficiency at high loads and excursion resiliency.
As of the publication date, it was launched at a promotional price of $399 USD, with the regular MSRP at $549 USD on the Cooler Master webstore, which is slightly higher than other Platinum power supplies but still competitively priced.
WHAT YOU NEED TO KNOW
THE GOOD
- Performance
Demonstrated good performance across the majority of the tests. One of the best-performing power supplies to date in power excursion in Labs testing.
- Resiliency
The X Silent Edge Platinum 850 is very resilient to brownouts, making it a reliable choice.
- Unique Design
It is the industry’s first fanless power supply to achieve 850W.
THE BAD
- Limitations
While the fanless design eliminates fan noise, there are the trade-offs of being heavier and also limiting on mounting orientations inside computer cases, as it cannot be installed upside-down or on its side.
THE REST
- Overall
We recommend the X Silent Edge Platinum 850 for its distinctive fanless design, strong performance, and solid resilience to brownouts. While it's somewhat expensive, it offers a reliable option for future-proofing your setup.
The Cooler Master X Silent Edge Platinum 850 is an ATX form factor power supply, and comes with a variety of accessories in the box, including highly flexible, individual cables with a braided pattern. Among these is a right-angled 12V-2x6 cable, designed for reliability and capable of delivering up to 600W to a GPU. In the Box, the power supply came very well packaged with very sturdy and dense foam, adding to the premium feel and price tag.
Notably, this PSU is fanless, relying instead on Cooler Master's composite heat pipe technology to passively dissipate heat from its electronic components. The design incorporates copper-sintered and copper-powdered textures to enhance heat dissipation efficiency.
Cooler Master specifies in their installation guide for this PSU that it must be installed upright with proper airflow on top. It is not recommended to orient the unit in the common inverted or side-mounted positions, and the heat dissipation vents should not be obstructed.
On the Cooler Master specifications webpage it specifies that the Operating Temperature is 0°C to 40°C, though we cannot verify this through testing.
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Front of the box.
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Top of the PSU displaying the fanless internals.

Side of the PSU displaying the specifications.
+12 V | +5 V | +3.3 V | +5 Vsb | -12 V | |
---|---|---|---|---|---|
CURRENT | 70.8 A | 20 A | 20 A | 3 A | 0.3 A |
WATTAGE | 849.6 W | 120 W | 15 W | 3.6 W | |
850 W |
Please note that the above ratings are manufacturer advertised specifications.
The X Silent Edge Platinum 850, being fanless, offers a single cooling mode. However, users can monitor temperature, current load, and overall performance digitally via Cooler Master's MasterCTRL software.
The PSU is equipped with all the standard protections expected for its class and is supported by an extensive 15-year warranty.
In the terms of performance, the X Silent Edge Platinum 850 delivered mixed results. It performed very well in load regulation, with the 12V rail showing a voltage drop of 0.107V across the full rated output, which is within ATX specifications and better than most power supplies we've tested.
However, the unit exhibited consistently high voltage ripple during testing. Although the 12V ripple remained within specifications, the 5V and 3.3V ripples exceeded the limits.
Despite this, the X Silent Edge Platinum 850 stands out as the best-performing power supply to date in power excursion in Labs testing, even though it produced some unusually shaped waveforms. Unlike previous power supplies we've tested, it exhibited no sharp voltage drops or spikes. It maintains stability even under the intense demands of the latest high-power GPUs.
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The X Silent Edge Platinum 850 is 80PLUS Platinum certified, achieving 92% efficiency at 50% of its maximum rated load. While it fell a bit short of the required efficiency at 20% load for both 115V and 230V, it achieved incredibly high efficiency at higher loads, reaching 94% efficiency at 230V under full load - exceeding the platinum requirement of 90% and the titanium requirement of 91%.
This PSU also demonstrated exceptional resilience to brownouts, successfully enduring a 24 ms dropout at full rated load for both 115V and 230V inputs. During our tests with brownouts lasting up to 26 ms, the unit sustained all except when delivering full load during a 26 ms brownout, where only the PG line dropped while the voltages remained steady.
The OPP engaged at a maximum of 126% of rated load, with the 12V rail alone capable of 88A, or 124% of its rating. This lower threshold, compared to similarly rated power supplies, helps protect components but may cause occasional shutdowns under extremely high loads.
