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An SFX power supply will fit only if the case supports its specific SFX profile and the exact PSU’s dimensions, mounting, cables, and airflow all clear. Check the case manual first, then compare the PSU’s published width, height, and depth with the usable PSU bay—not the outside of the case.
What to measure before buying
Use the case manual or manufacturer drawing to identify the supported PSU type, mounting orientation, and maximum dimensions. Then compare those limits with the dimensions published for the exact PSU model. If the case uses a bracket or adapter, include it in the fit check.
Measure the bay’s usable width, height, and depth. Depth runs from the PSU mounting plane to the first obstruction. Keep the axes consistent with the PSU manufacturer’s dimension listing, and account for anything that reduces the open space, such as a drive cage, radiator, fan, or cable bundle. Case exterior dimensions do not tell you how much room is available inside the PSU bay.
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“SFX” is not enough to confirm a match. Intel’s SFX12V Specific Guidelines distinguish several physical-outline profiles, including lower-profile, top-fan, reduced-depth top-fan, standard SFX, and PS3. Check which profile the case supports and compare it with the PSU’s stated form factor and mechanical outline. Intel’s linked design-guide PDF is version 2.11; the guidelines page is titled version 4.0 and notes that a newer version is available, so verify the applicable revision rather than treating that PDF as the latest edition.
#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.
Use the exact product page or manual for dimensions, not a generic SFX figure. For example, Seasonic Industrial lists 100 × 125 × 63.5 mm for its SFX SFP/SFG family. That is a specification for that family, not a universal size for every PSU sold as SFX.
Verify mounting and the installation envelope
A PSU body can fit inside the bay and still fail to install or operate properly. Check the applicable case and PSU drawings or manuals for the mounting-hole pattern, rear cutout, and allowed orientation. Intel’s design guide includes PSU outline and chassis cutout drawings; use the drawing for the relevant profile.
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
- Connections and access: Make sure the AC inlet and power switch remain accessible after installation.
- Cable routing: Check where fixed or modular cables exit and whether there is room to route and bend them without pressing against a panel or blocking another component. The cited standards do not establish a universal cable-bend clearance.
- Nearby components: Confirm that drive cages, fans, radiators, and cable bundles do not obstruct installation or occupy required PSU space.
- Ventilation: Preserve the PSU’s intended intake and exhaust path; do not block its fan or ventilation openings.
- Installation access: Confirm there is room to insert and secure the PSU, not just room for its final position.
Where the case or PSU instructions do not resolve a clearance question, ask the manufacturer before purchase rather than assuming the part will fit.
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Use this go/no-go check
- Find the case manual or manufacturer drawing and note supported PSU profiles, dimensions, orientation, and any required bracket or adapter.
- Measure the clear bay width, height, and depth, including the distance from the mounting plane to the first obstruction.
- Look up the exact PSU model’s published dimensions and form factor.
- Confirm the mounting pattern and rear cutout match in the intended orientation.
- Check cable exit and bend room, inlet and switch access, nearby components, and unobstructed ventilation.
Count the fit as confirmed only when the case supports the PSU profile and the body, mounting, cable routing, and ventilation all clear. If you cannot verify a dimension or orientation, contact the case or PSU manufacturer before ordering.
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.
Keep physical fit separate from electrical suitability
A PSU that fits physically is not necessarily suitable for the build. Check wattage, connectors, and electrical requirements separately against the system’s components and the PSU specifications. For example, be quiet!’s SFX Power 3 product page lists SFX12V Version 3.42 and 450 W continuous power with 500 W peak power; those are specifications for that product, not criteria for physical fit.
Quick Recap
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