We start each article, where we present a power supply, with a disclaimer that we can’t tag this as a full review since we don’t own a load tester.

When it comes to small form factor builds, a quality SFX is a mission priority item, especially with more and more power hungry GPUs and newer protocols. Before the implementation of the plagued 12VHPWR cable from Nvidia, well the best unit you could get was the Corsair SF750W. Alas, building a brand new system which includes the latest SFX12V 4.0 & PCIe 5.0 protocols, the new champion looks to be this SFX unit from SilverStone, the Extreme 850R Platinum.

SilverStone Technology Co., Ltd is a company based in Taiwan, founded in 2003 that makes computer cases, power supplies, and other peripheral for personal computers. Their goal was to provide products that create inspirations and customers a wide selection of choices.

With distribution centres in different areas of the globe, SilverStone products can be seen all over the world, not just for computer users but also for home entertainment use. Thus providing leisure with integration of advanced technologies that is functional and making them enjoyable to use.


Prices and Availability


As one might expect, acquiring the latest and most advanced technology often comes with a higher price tag. In this case, it’s worth noting that this PSU boasts a Platinum rating and is accompanied by a 5-year warranty, contributing to its overall value


Highlights and Specification


*Courtesy of their website.

Extreme 850R Platinum – Cybenetics Platinum 850W SFX12V 4.0 & PCIe 5.0 Fully Modular SFX Power Supply

* Equipped with Gen5 12VHPWR PCIe connector, meeting Intel SFX 12V V4.0 specification standard
* Cybenetics Platinum efficiency certification
* 24/7 continuous power output with 50℃ operating temperature
* Ultra-silent 92mm FDB fan with fan intelligent deactivates and delayed shut off function
* Flexible flat cables have much greater flexibility to allow for tighter folding
* Fully Modular design
* All Japanese electrolytic capacitors


Visual Inspection and Installation


IT comes shipped in the classic SilverStone livery with primarily blue and white colors.

All the main features are well distributed across all sides. On the back for example, we learn that this is a single +12V rail design and it meets Intel’s newest SFX12V 4.0 & PCIe 5.0 specs. Thus it featues one 450W rated 12VHPWR 16-pin cable.

It offers an ATX to SFX bracket which is highly useful to have.

On the left you have the regular Philips main securing screws while on the right, those are if you plan to use the above bracket.

Protection is excellent since the PSU has its own foam cocoon while the cables reside in the other half of the box.

Here are all the cables that you will receive. Unfortunately they aren’t sleeved nor are they flexible to bend.

The main attraction is the 450W rated 12VHPWR 16-pin cable.

Here is the complete list:

1x 24/20-Pin motherboard connector
2x 8/4-Pin EPS / ATX 12V connector
2x 8/6-Pin PCIe connectors
1x 12+4-Pin 12VHPWR connector
8x SATA connectors
3x 4-Pin Peripheral connector
1x 4-Pin Floppy connector

This being an SFX PSU, don’t expect long cables for an ATX build without extensions.

The 850W rated SFX unit possesses an incredible 1070W per liter density considering its 125 mm (W) × 63.5 mm (H) × 100 mm (D) dimensions.

It’s refreshing to see the ability to select the hybrid mode for the fan.

It features a Cybenetics Platinum certification (≥89% & <91% overall efficiency) and all the protection protocols under the sun. It's build, of course, using Japanese all solid caps.

All the connectors are nicely flush within the body, unlike other high wattage SFX units.

Cooling is provided by a fluid dynamic bearing 92mm fan which can spin up to around 2200 RPM.

Perspective is everything, as in how small and compact the SilverStone 850W SFX unit is when compared to a 150mm long ATX 750W power supply.

For our test build, these are the cables that we will use. Since it’s an ATX build, we will need to use the included bracket as well.

The cables and connectors form a secure connection.

As expected, the included cables will be too short for an ATX tower build and thus we installed extensions for the CPU and mainboard ports. Surprisingly the PCI-E cable was long enough to reach out test motherboard.

We need to point out that the included cables are hard to bend no matter the intended enclosure and thus custom ones are highly encouraged for those extreme SFF builds. Also we appreciate the dual EPS feature of the PSU but given its high wattage, you will be forced to acquire an adapter if your high end GPU has more than 2x 6+2 ports.


Testing methodology


  • The SilverStone 850W SFX Platinum rated will be tested at idle, then in a gaming scenario and finally at full system load in stress test
  • The CPU & GPU will be mildly overclocked to 3.8 MHz @ 1.30v and Power limit 110, Core +100 and Memory +400 MHz respectivly.
  • In order to verify the efficiency of the PSU, the power draw of the system was measured at the wall socket then the voltages were taken on the rails using a multimeter
  • As the main torture test, we will employ a CPU & GPU 2-minute run in AIDA64
  • Room temperature was recorded at ~23°C
  • For the noise output, a specific test was performed with a close up mic placement
  • All of the side panels will be attached

Testing platform:

CPU: AMD Ryzen 7 2700
CPU Cooler: Alpenföhn Brocken 4 120mm Single Tower
RAM: 16GB DDR4 Crucial LPX Vengeance 3200 MHz CL16
Motherboard: ASUS ROG STRIX B450-F Gaming II ATX @ BIOS 5102
Boot SSD: Samung 840 PRO 256GB MLC SATA III SSD
Video card: MSI GTX 970 4G OC
Case: be quiet! Pure Base 500 FX ARGB Tower ATX


OS: Windows 10 Pro x64 Version 22H2
NVIDIA Drivers536.40
CPU-Z v1.95To verify the CPU’s and RAM’s statistics
Core Temp v1.18 & HW Monitor v1.51 – To see the temperatures in real time
AIDA64 Extreme v6.60Memory analysis and Benchmark suite
MSI Afterburner v4.64 – To record the FPS and load/temperatures
Cinebench R23Great overall CPU benchmark tool
3D/Game(s)Rise of the Tomb Raider, set at 1080p, high quality settings, no V-Sync


Installation, Testing, Results and Analysis


As mentioned, the PSU unit will be tested in 3 different scenarios, idle, gaming scenario to simulate a real life usage and finally a torture test with the GPU & CPU at max load, in OC settings. The testing system peaked at around 391W, which is roughly 46% load from the total 850W available and thus we proceeded to measured the efficiency rating. Since both the CPU and GPU are overclocked, without an adaptive voltage for the CPU, this is why we have such high idle figures.

As you can see the unit, at almost 50% load, is bang on regarding its advertised Platinum certification. Unfortunately we didn’t have on hand an RTX GPU that features the 12VHPWR port to test out that cable but we will revise in the future if the situation changes.

Regarding the noise output, the unit operates at a relatively quiet level, comparable to the Corsair 750W SFX unit. It features a hybrid mode, meaning the fan engages after reaching a load of 200W. It remains at a low RPM, typically under 1500, until reaching around 650W load. As it approaches its maximum capacity, it may reach a maximum RPM of approximately 2200. Here is a quick recording while a total system stress was being performed. Also worth mentioning that the fan even has a delayed shut off function, which means it will spin a few seconds more after you shutdown the computer, for maximum heat control.




At the time of writing, SilverStone’s Extreme 850R Platinum PSU is the only power supply available in a true SFX format that offers nearly the complete package: features, build quality, efficiency, and low noise output. At 850W, it stands as the most powerful option without venturing into the SFX-L category or having ports protruding beyond the unit’s dimensions, as seen in upcoming CoolerMaster SFX 1100W/1300W PSUs. It’s more than capable of handling demanding configurations like the i9 13900K and RTX 4090 combo without overclocking. As an extra peace of mind, you can always undervolt them since it’s proven so many times, that you can get stock performance with less heat. Notably, the drawbacks aren’t associated with the PSU itself but rather concern the supplied cables. They are excessively rigid, which poses challenges in an SFX build where every millimeter of space counts. Also, it doesn’t have more than 2x 6+2 PCI-E cables, preferring to offer 2x EPS ports. While this configuration is acceptable, including an EPS to PCI-E adapter would have been a valuable addition. In summary, the SilverStone Extreme 850R Platinum PSU is a robust choice for those seeking maximum power in their SFF builds without the need to upsize.

The good:

+ One of the most potent and capable PSUs in a true SFX format
+ Sufficient power to run an RTX 4090 and i9 13900k combination
+ Robust build quality
+ Includes 2x CPU EPS cables
+ Equipped with a 450W 12VHPWR port
+ Operates quietly
+ Single +12V rail design
+ Offers a hybrid fan mode
+ 5 years warranty
+ ATX to SFX bracket included

The bad:

– Unsleeved cables
– Cables are stiff and challenging to bend
– Higher price point
– Lack of an EPS to PCIe adapter, which could be useful for those using older GPUs requiring more than 2x 8-pins for power delivery

Glob3trotters “High Density” Award – 4.5 out of 5


Many thanks to SilverStone for supplying us with this unit!

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