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Repair Windows errors before they cause bigger problemsFix Now →Scan for outdated or missing drivers - takes under a minuteDriver Scan →An SFX power supply fits only if the case supports its exact SFX profile and the PSU’s body, mounting, cables and ventilation all clear the usable bay. Check the case manual and the exact PSU’s published dimensions before buying; “SFX” by itself does not guarantee compatibility.
What to measure in the case
Measure the usable PSU bay, not the outside of the case. The three relevant dimensions are width, height and depth, taken along the same axes used in the PSU manufacturer’s specification. Depth is especially easy to overestimate: measure from the PSU mounting plane to the first obstruction.
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Start with the case manual or manufacturer’s drawing. Record the supported PSU type or profile, allowed orientation and maximum dimensions. If those details are unavailable, measure the clear space inside the bay directly, and account for anything that occupies or restricts it.
- Check whether a drive cage, radiator, fan or existing cable bundle reduces the bay.
- Include any bracket or adapter the case requires.
- Do not assume that a large external case measurement represents the space available to the PSU.
Find the exact PSU dimensions and profile
Look up the specific PSU model in its manufacturer’s specifications or manual. Compare its listed width, height and depth with the case’s usable limits. Do not substitute a generic SFX dimension: Intel’s SFX12V design guide distinguishes several physical-outline profiles, including lower-profile, top-fan, reduced-depth top-fan, standard SFX and PS3. Verify the profile the case actually supports.
#1 Best Overall
- 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.
As one product-family example—not a universal SFX size—Seasonic Industrial lists its SFX SFP/SFG units at 100 × 125 × 63.5 mm. The Intel guide provides mechanical outlines and chassis cutout drawings for the applicable profiles. Its linked PDF is version 2.11 and includes the SFX12V Specific Guidelines 4.1 chapter; the associated Intel web page is titled “SFX12V Specific Guidelines 4.0” and notes that a newer version is available. Consult the applicable drawing and verify the current revision rather than treating that PDF as the latest edition. Intel SFX12V guidelines; Seasonic Industrial SFX SFP/SFG specifications.
Confirm mounting and installation clearance
A PSU can be small enough for the bay and still fail the fit check. Confirm the screw pattern and rear cutout match the case in the intended orientation. Intel’s mechanical drawings are useful for checking outlines and cutouts, but they do not establish a universal cable-bend or case-side clearance allowance.
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
- Access: Make sure the AC inlet and power switch remain accessible after installation.
- Cables: Check where fixed or modular cables exit and whether there is room to connect and route them without forcing a sharp bend or blocking adjacent components.
- Obstructions: Check the route around drive cages, fans, radiators and other installed hardware.
- Airflow: Preserve the PSU’s intended fan intake and exhaust path; do not obstruct its ventilation.
- Installation: Allow enough room to insert and fasten the PSU, not just enough room for its final body position.
Use the case and PSU manufacturers’ installation instructions to resolve clearances not given in their dimension tables. If an orientation or cable route cannot be verified, ask the manufacturer before purchase.
A practical go/no-go check
- Read the case documentation. Note supported PSU profiles, orientation, bay limits and any required bracket or adapter.
- Establish the available space. Use the case drawing or measure the clear internal width, height and depth from the mounting plane to the first obstruction. Include installed hardware in that check.
- Record the exact PSU specifications. Use the model’s own published dimensions and form factor, not a generic SFX figure.
- Compare body and mounting. Confirm all three dimensions fit and that the mounting holes and rear cutout work in the selected orientation.
- Check the full installation envelope. Verify access, cable connection and routing, insertion room, nearby components and ventilation.
- Decide only when every check passes. Treat fit as confirmed when the case supports the profile and the exact PSU body, mounting, cables and airflow all clear. If a required dimension or detail remains uncertain, get confirmation from the case or PSU manufacturer.
Physical fit is separate from electrical suitability
A PSU that fits physically is not necessarily suitable for the system. Separately check its power capacity and connectors against the components and the PSU’s specifications. For example, be quiet! lists its SFX Power 3 as SFX12V Version 3.42 and specifies 450 W continuous power and 500 W peak power; those are product specifications, not evidence that it fits a particular case. be quiet! SFX Power 3 specifications.
Quick Recap
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.
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