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SFX-L is generally 30 mm deeper than SFX, while the listed width and height are the same. That extra length can allow a larger fan in some designs, but it does not guarantee quieter or cooler operation, more power, or compatibility with every SFX case. Check the exact power supply’s dimensions against the case’s clearance, then verify cables, connectors, wattage, and mounting.
What is the difference between SFX and SFX-L?
The main distinction in CORSAIR’s comparison is depth: SFX is listed as 100 × 125 × 63.5 mm and SFX-L as 130 × 125 × 63.5 mm, with measurements given as depth × width × height. That makes the SFX-L example 30 mm deeper; its listed width and height are unchanged. CORSAIR’s comparison is useful for orientation, but always check the exact model’s specification because manufacturers may report length and width in a different order.
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For example, Seasonic lists its standard-SFX FOCUS SGX (2021) as 125 mm (L) × 100 mm (W) × 63.5 mm (H), the same envelope as CORSAIR’s SFX dimensions when the axes are aligned. be quiet! lists its SFX L Power 600W at 130 × 125 × 64 mm (L × W × H). Those product examples illustrate the naming distinction; they do not establish that every retail unit has identical dimensions.
How the names relate to the formal SFX specification
Intel’s public ATX12VO Desktop Power Supply Design Guide labels its relevant section “SFX12V Specific Guidelines 4.1” and describes SFX12V mechanical profiles. The reviewed passage says those dimensions have not changed from Multi Rail Desktop Power Supplies. It does not define the retail SFX-L label as a distinct standardized profile, so treat SFX-L here as the extended-depth market form factor shown in manufacturer product specifications.
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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 does not automatically have room for an SFX-L unit. The extra depth can meet a drive cage, fan, radiator, GPU arrangement, or the space needed for modular plugs and cable bends. Use the case maker’s maximum PSU length and the exact unit’s published dimensions rather than relying on the form-factor label alone.
- Find the case limit. Check the case manufacturer’s supported PSU types and maximum PSU depth or length.
- Check the exact PSU dimensions. Compare its length or depth with the case limit, using the same axis order. Account for any protrusions the manufacturer includes in its measurement.
- Allow room for cables. Check the clearance behind modular sockets and whether cables can bend without pressing against panels or nearby hardware.
- Check nearby components. Confirm that the unit and its cables will not interfere with drive cages, fans, radiators, or the planned GPU layout.
- Confirm mounting and airflow. Check the PSU opening, any required adapter bracket, the fan’s intake direction, and the space available for intake air.
Clearance is case- and model-specific. If the case specification does not make cable or component clearance clear, consult the case maker’s compatibility guidance before buying.
Does SFX-L run cooler or quieter than SFX?
No general guarantee follows from the form factor. A longer enclosure can give a manufacturer room to use a larger fan, but fan size alone does not determine noise or temperature. Fan control, internal thermal design, PSU load, and the case’s airflow all affect results.
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- 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
Product examples show why it is better to compare models than labels: be quiet!’s SFX L Power 600W has a temperature-controlled 120 mm fan, while Seasonic describes hybrid fan control on its standard-SFX FOCUS SGX (2021). Intel’s design guide describes a standard-profile airflow path in which “The fan will draw air from the computer system cavity pressurizing the power supply enclosure,” with air exhausting through a rear-panel grill. That is a description of the specified airflow design, not evidence that one retail form factor is quieter or cooler than the other.
For a meaningful acoustic or thermal comparison, look for independent tests of the specific models at comparable loads and ambient conditions. The cited manufacturer specifications and Intel design guidance do not provide a controlled head-to-head performance comparison.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What else should you check before choosing?
Wattage and connectors
Choose a unit with adequate continuous wattage for the complete system and the motherboard, CPU, and GPU connectors your components require. SFX or SFX-L describes the physical form factor; it does not establish electrical suitability or superiority.
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.
Modular cable compatibility
Do not assume modular cables can be carried over from another PSU, even if it is from the same brand. CORSAIR says its SFX units use Type 4 cables while its SFX-L units use Type 5 Gen 1 micro-fit cables. Check the manufacturer’s compatibility information for the exact PSU and cable set before reusing any cables.
Mounting bracket and other accessories
Bracket contents vary by model. Seasonic lists an SFX-to-ATX adapter bracket with the FOCUS SGX (2021), and be quiet! lists one with the SFX L Power 600W. Check the product’s package contents if you need to fit the PSU in a larger opening; do not assume a bracket is included or buy a duplicate without checking.
Model-level comparison
Once both candidates fit, compare their actual specifications and credible independent electrical reviews. The form-factor name cannot tell you which model is the better match.
Quick Recap
- Exact dimensions and case clearance, including cable space
- Fan size and control method, plus independent noise and temperature measurements
- Continuous wattage and the connector set
- Modular cable type and manufacturer-approved compatibility
- Efficiency certification and model-specific electrical test results
- Included brackets, other accessories, and warranty terms
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.
