SilverStone Extreme 1200R Platinum SFX-L PSU review

SilverStone is a prominent manufacturer in the PC hardware industry, known for producing high-quality components such as power supply units (PSUs), cases, and cooling solutions. SilverStone’s products are often characterized by their compact, power-dense designs and commitment to efficiency, making them a popular choice for small form factor builds and high-performance systems alike. 

The SilverStone Extreme 1200R Platinum (EX1200R-PL) SFX-L PSU is a powerful solution designed to meet the needs of compact yet high-performance systems. With a power output of 1,200 W and compliance with ATX 3.1 / SFX12V V4.1 standards, it offers a robust feature set, including individually sleeved cables and a 12+4 pin (12V-2×6) connector for seamless compatibility with the latest high-performance graphics cards. Achieving 80 Plus Platinum efficiency, the Extreme 1200R is positioned for enthusiasts and professionals who demand top-tier performance, efficiency, and reliability in a space-saving form factor.

Specifications and Design

In the Box

The SilverStone Extreme 1200R Platinum SFX-L PSU arrives in a durable and glossy cardboard box, reflecting the blue and mustard theme SilverStone has been using for some time. The PSU is safely housed within a nylon pouch and protected by packaging materials to ensure secure transit. 

The bundle includes mounting screws, an AC power cable, four basic cable straps, and a few cable ties. Additionally, SilverStone includes an SFX-to-ATX case adapter, though users should be aware that the relatively short cables may present challenges when installed in larger ATX cases.

The PSU features all-black cables with individually sleeved wires, enhancing aesthetics and offering greater flexibility. The inclusion of a single 12+4 pin (12V-2×6) connector and two 6+2 pin PCI Express connectors on the same cable ensures compatibility with modern GPUs, though the overall number of connectors is relatively low for a unit of this power rating. Despite this, the Extreme 1200R stands out for its clean design and efficient cable management, making it a solid choice for demanding small-form-factor builds. 

External Appearance

The SilverStone Extreme 1200R Platinum SFX-L PSU is housed in a sleek, matte black chassis measuring 130 mm in length, making it larger than standard SFX units. This extended size is typical of SFX-L units and is important to consider for compatibility with compact cases.

The PSU’s finish is smooth and elegant, with the detachable fan finger wire guard featuring the traditional concentric design, complemented by SilverStone’s metallic badge at the center. Decorative stickers showcasing the company and series logo adorn both the left and right side, while the top is reserved for a label displaying the electrical specifications and certifications.

The rear of the PSU includes the standard on/off switch, AC power receptacle, and a hybrid fan mode switch. Disabling the hybrid fan mode will force the fan to be always on but the fan’s speed remains thermally controlled, maintaining a very low speed while the cooling demand is low. The front of the unit houses the modular cable connectors, with a legend for easy identification. Notably, the connectors slightly protrude from the PSU’s body, and some of them have protective plastic caps.

Internal Design

The SilverStone Extreme 1200R Platinum SFX-L PSU uses a 120mm low-profile Globe S1201512HBP-4M fan with a ball-bearing engine. It has impressive air flow specifications for a low profile fan but it should not be compared to a normal thickness fan. The fan of this unit shouldn’t have to work overtime as the PSU has a zero-RPM mode. It has a maximum speed of 2,100 RPM, relatively high for a 120 mm low-profile model.

SilverStone’s Extreme 1200R is built on a platform by Enhance Electronics, a reputable OEM known for its advanced PSU designs. Internally, the unit is densely packed, with great attention to maximizing space efficiency. The filtering stage is robust, featuring four Y capacitors, three X capacitors, and two filtering inductors, a commendable configuration for a unit where space comes at a premium.

The rectifying bridges are mounted on a heatsink right after the filtering stage. The APFC circuit includes two OSG55R070H MOSFETs and one UJ3D065 diode mounted on a heatsink, with two Rubycon 470 μF capacitors providing passive support. Interestingly, these capacitors are rated at 85°C, which is less common in high-end PSUs where 105 degrees Celsius ratings are the norm. The primary stage uses four Oriental Semi OSG55R160FZ MOSFETs in an LLC resonant topology. These are found on another heatsink right after the PFC stage, next to the two compact encased transformers of the unit.

Eight MOSFETs found at the underside of the PCB generate the primary 12V line, with illegible markings. The only thing we know about those is that they are so efficient that they are primarily cooled just via the thermal pad that thermally connects them to the chassis. It is a synchronous rectification topology. DC-to-DC circuits on a vertical daughterboard at the main PCB’s edge generate the 3.3V and 5V lines. The secondary capacitors are all rated at 105°C and supplied by  Rubycon, Nichicon, and Unicon — all Japanese companies.

Cold Test Results

Cold Test Results (25°C Ambient)

For PSU testing, we are using high precision electronic loads with a maximum power draw of 2,700 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 SilverStone Extreme 1200R Platinum SFX-L PSU comfortably meets the Cybenetics Platinum certification requirements across different input voltages. It would probably lose the 80 Plus Platinum certification due to the efficiency dip at maximum load, which at 100% load is just a breath under the certification’s limit. With a 115 VAC input, the PSU achieves an average nominal load efficiency of 90.2%, improving to 92.4% when using a 230 VAC input. The efficiency peaks around 50% load, which is typical for most PSUs. Although there is a measurable 2.2% efficiency drop when using a 115 VAC input, the unit still meets the Cybenetics certification’s requirements. Its performance at very low loads is also commendable.

The fan in the SilverStone Extreme 1200R starts operating when the PSU reaches approximately 30% capacity. It remains fairly quiet at lower loads but gradually increases in speed as the load rises. Even under full load, the fan does not reach its maximum speed when the PSU is operating at room temperature, but it will definitely be audible even in a busy room. Internal temperatures remain well within safe limits under these operating conditions.

Hot Test Results

Hot Test Results (~45°C Ambient)

During hot testing, the SilverStone Extreme 1200R Platinum SFX-L PSU experiences a very slight decrease in efficiency under heavy loads, with efficiency figures dropping to 89.7% at 115 VAC and 91.9% at 230 VAC, compared to 90.2% and 92.4% during cold testing. This efficiency degradation of about 0.5% is negligible, indicating that the unit handles high ambient temperatures exceptionally well, without significant thermal stress on its components.

In these hotter ambient conditions, the fan of the SilverStone Extreme 1200R activates slightly earlier than during cold testing, starting at around 200 watts of load. It ramps up progressively as the load increases, reaching maximum speed when the unit operates under sustained heavy loads. Although the fan becomes very loud at maximum speed, this is expected given the compact SFX-L design and the use of a low-profile fan. Despite this, the unit’s internal temperatures remain well-controlled, a small miracle for such a dense and powerful design.

PSU Quality and Bottom Line

Power Supply Quality

The SilverStone Extreme 1200R Platinum SFX-L PSU delivers fairly good electrical performance that stands out when compared to SFX units. It showcases good voltage regulation, with the 5V rail maintaining a 1.2% deviation, the 3.3V rail at 1.6%, and the 12V rail at 1.4%. In terms of ripple suppression, the 1200R Platinum performs exceptionally well for such a compact, power-dense unit. The measured maximum ripple values are 62 mV on the 12V line, 28 mV on the 5V line, and 24 mV on the 3.3V line, figures maxing just above half of what the design guide dictates as the limit. While ATX units typically have slightly better ripple suppression, these results are outstanding considering the high power density of the SFX-L form factor.

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 SilverStone Extreme 1200R Platinum passed all these critical protection tests without issues.

The OCP settings for the 3.3V and 5V rails are set to activate at 140%, aligning with the unit’s high combined output for these rails. The 12V rail’s OCP is set at 124%, a well-calibrated threshold for a unit of this power density, ensuring the PSU can handle short-term overloads without sacrificing safety or performance.

Bottom Line

The SilverStone Extreme 1200R Platinum SFX-L PSU is a premium power supply unit that sets itself apart through its compact design, exceptional electrical performance, and high power output. Retailing at $330, it is undoubtedly a high-end product targeting a niche group of users — primarily enthusiasts and professionals looking for high wattage in compact systems. While the price point is steep, the PSU offers a feature set and performance that justifies the cost for those who need this level of power and efficiency in an SFX-L form factor.

One of the most notable aspects of the Extreme 1200R is its ability to deliver 1200 Watts of power while maintaining Platinum-level efficiency. It comfortably meets Cybenetics Platinum certification requirements, with minimal efficiency drop under high ambient temperatures. This performance is a significant achievement given the constraints of the SFX-L form factor, where space is at a premium. Despite the spatial constraints, the power quality of the Extreme 1200R is very good, maintaining good voltage regulation and delivering fair voltage filtering for such a power-dense unit.

Thermal management may be exceptional considering the very compact dimensions of the unit but, from a consumer’s point of view, it leaves room for criticism. The low-profile 120 mm fan does a great job but the noise level ramps up significantly under heavy loads. While this is somewhat expected given the power density of the unit, the noise profile at higher loads may deter users who prioritize quiet operation, as the acoustics performance does not stand out in a way that justifies the very high cost.

The build quality is another area where SilverStone seems to have made compromises. While the internal components, such as Rubycon and Nichicon capacitors, are of high quality, the use of 85°C-rated capacitors in the APFC stage raises some concerns about longevity under heavy, sustained loads. Additionally, the compact design means that some components are crammed into place with glue, an approach that feels less than premium for a product of this class. Furthermore, the short cable length and relatively low number of connectors could be an issue for users intending to use this PSU in ATX systems or larger cases. The included SFX-to-ATX adapter helps with compatibility, but the number and length of the cables may limit both compatibility and flexibility if moving to a larger case.

The SilverStone Extreme 1200R Platinum SFX-L PSU is an ambitious, powerful, efficient, and fairly well-designed unit for those building compact, high-performance systems. However, its $330 price tag positions it at a very unique market position, making it difficult to recommend to anyone but the most dedicated enthusiasts who absolutely need a high-wattage PSU in a small form factor. For those who do seek top-tier performance in a compact footprint, the SilverStone Extreme 1200R Platinum SFX-L will not disappoint.

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