The Tool Desk
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What is the difference between SFX and SFX-L?
The main difference is depth. In CORSAIR’s comparison, SFX measures 100 × 125 × 63.5 mm and SFX-L measures 130 × 125 × 63.5 mm. CORSAIR gives the order as depth, width, height, so the SFX-L example is 30 mm deeper, with the same listed width and height. CORSAIR’s SFX and SFX-L comparison is an example of manufacturer-listed dimensions; always check the specification for the exact unit you are considering.
Manufacturers may list dimensions in different orders. For example, Seasonic specifies its standard-SFX FOCUS SGX (2021) as 125 mm (L) × 100 mm (W) × 63.5 mm (H), the same envelope as CORSAIR’s SFX figures with length and width reported in a different order. Be quiet! lists its SFX L Power 600W as 130 × 125 × 64 mm (L × W × H). Seasonic’s FOCUS SGX (2021) specifications and be quiet!’s SFX L Power 600W specifications illustrate why it is important to read the dimension labels, not just the numbers.
Intel’s ATX12VO Desktop Power Supply Design Guide includes SFX12V-specific mechanical guidelines, but the reviewed section does not define “SFX-L” as a separate standardized dimension. Treat SFX-L as the extended-depth retail form factor reflected in manufacturer product specifications, rather than assuming that the label alone guarantees one exact measurement across products. Intel’s ATX12VO Desktop Power Supply Design Guide
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- Fully Modular PSU: Reliable and efficient low-noise power supply with fully modular cabling, so you only have to connect the cables your system build needs.
- ATX 3.1 Certified: Compliant with the ATX 3.1 power standard, supporting the PCIe Gen 5.0 platform and resisting transient power spikes.
- Low-Noise Fan: Equipped with a premium 92mm FDB (Fluid Dynamic Bearing) fan, the PSU ensures efficient and quiet thermal performance.
- Native 12V-2x6 Connector: SP Series V2 Gold features a two-tone 12V-2x6 power cable with visual cues for safe connections, enhancing clarity and reliability for high-performance 50/40 series graphics cards.
- Upgraded Standby Power & Reliable Power Backed by 10-Year Hardware Protection: The SP Series V2 Gold features an upgraded 5VSB (standby) rail, increasing its current capacity from 2.5A to 3A, better supporting today's power-hungry peripherals.
Will an SFX-L power supply fit in an SFX case?
Not necessarily. A case that supports SFX may have room for only the shorter depth, or it may lack clearance for the PSU’s plugs and cables. Compatibility depends on the exact PSU and case, as well as nearby components—not just the form-factor label.
- Check the case specification. Find the case maker’s supported PSU formats and maximum PSU length or depth.
- Compare the exact PSU dimensions. Use the model’s manufacturer specification and confirm which dimension is length/depth. Account for any protrusions the manufacturer includes in its measurement.
- Check room around the unit. Allow for modular plugs and cable bends, and look for interference with drive cages, fans, radiators, or the graphics-card arrangement.
- Confirm intake clearance and airflow. Make sure the PSU fan can draw air in the direction intended by the PSU and case design.
- Verify the electrical fit. Confirm continuous wattage and the motherboard, CPU, and GPU connectors required by the complete system.
- Check the mounting hardware. If the case has a larger PSU opening, confirm whether the exact PSU package includes an adapter bracket or whether one is needed.
Brackets are product-specific accessories, not a universal SFX or SFX-L inclusion. Seasonic lists an SFX-to-ATX adapter bracket with the FOCUS SGX (2021), and be quiet! lists one for the SFX L Power 600W. Check the package contents of the model you buy. Seasonic FOCUS SGX (2021); be quiet! SFX L Power 600W
Is SFX-L quieter or cooler than SFX?
No form-factor label can establish that. SFX-L’s additional depth can give a manufacturer room to use a larger fan, but cooling and noise depend on the particular PSU’s fan size and control, thermal design, load, and the airflow around it. For example, be quiet! lists a temperature-controlled 120 mm fan in its SFX L Power 600W, while Seasonic describes hybrid fan control in its standard-SFX FOCUS SGX (2021). Those model-specific designs do not prove that SFX-L products as a group are quieter or cooler.
Rank #2
- Compact Power Solution: APEVIA SFX-AP500W 500W Power Supply designed for Mini ITX Solution, Micro ATX, and SFX form factor systems
- Comprehensive Connector Options: Includes 1 x 20+4pin Main Power, 1 x 8pin 12V(P4+4), 1 x 6/8pin PCIe, 3 x SATA, and 2 x 4pin Molex connectors for versatile compatibility
- Space-Saving Dimensions: Measures 125mm x 100mm x 63.5mm (4.9 inches x 3.94 inches x 2.5 inches) - L x W x H, designed for small form factor builds
- Proper Installation Required: The power supply will not power on simply by connecting the power cord to both the power supply and wall outlet. Ensure that all the power supply cables are properly connected to the PC for it to power on
- Flexible CPU Power Connection: The 8pin CPU connector can be split apart to become a 4+4 by pushing one end of the 4pin down and the other end of the 4pin up for motherboards that require a 4pin power
Intel’s design guide describes airflow in its standard profile this way: “The fan will draw air from the computer system cavity pressurizing the power supply enclosure.” The guide also describes rear-panel exhaust. Its specified airflow path explains the PSU’s role in a system, but it is not a performance comparison between modern retail SFX and SFX-L units. Intel’s ATX12VO Desktop Power Supply Design Guide
To choose between two specific models for acoustics or temperatures, look for independent tests conducted at comparable loads and ambient conditions. A larger fan or longer enclosure alone is not enough to predict the result.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Can you reuse modular cables between SFX and SFX-L PSUs?
Do not assume so, even if both units are from the same manufacturer. CORSAIR says its SFX units use Type 4 cables while its SFX-L units use Type 5 Gen 1 micro-fit cables. That example shows that cable families can differ within one brand; verify the exact PSU model against its manufacturer’s cable compatibility information before reusing any modular cable. CORSAIR’s SFX and SFX-L comparison
Rank #3
- Fully Modular PSU: Reliable and efficient low-noise power supply with fully modular cabling, so you only have to connect the cables your system build needs.
- ATX 3.1 Certified: Compliant with the ATX 3.1 power standard, supporting the PCIe Gen 5.0 platform and resisting transient power spikes.
- Low-Noise Fan: Equipped with a premium 92mm FDB (Fluid Dynamic Bearing) fan, the PSU ensures efficient and quiet thermal performance.
- Native 12V-2x6 Connector: SP Series V2 Gold features a two-tone 12V-2x6 power cable with visual cues for safe connections, enhancing clarity and reliability for high-performance 50/40 series graphics cards.
- Upgraded Standby Power & Reliable Power Backed by 10-Year Hardware Protection: The SP Series V2 Gold features an upgraded 5VSB (standby) rail, increasing its current capacity from 2.5A to 3A, better supporting today's power-hungry peripherals.
How to compare SFX and SFX-L PSU models
Once both units fit the case, compare the actual specifications and evidence that matter to your build:
- Fit: Exact depth, case clearance, cable-bend room, and nearby-component clearance.
- Cooling and noise: Fan size and control, plus independent thermal and acoustic measurements at comparable loads.
- Electrical support: Continuous wattage and the connector set required by the system.
- Cables: Cable family and manufacturer-confirmed modular-cable compatibility.
- Other model specifications: Efficiency certification and model-specific electrical reviews.
- Installation details: Included brackets and other accessories, along with warranty terms.
Form factor answers a broad physical-size question. It does not by itself establish a PSU’s electrical or acoustic superiority.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
