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Choose a power supply that matches the PSU bay in your exact case. Compact cases may require SFX or SFX-L; standard ATX cases commonly accept ATX units. SFX can often be mounted in an ATX case with a compatible adapter bracket, but its cables may be too short for a larger chassis. Check the case manual and the PSU’s exact dimensions before buying.
What is the difference between ATX, SFX, and SFX-L?
These labels describe a power supply’s physical envelope and mounting format. They do not, by themselves, indicate wattage, efficiency, connectors, noise, or build quality.
Corsair’s undated form-factor guide, accessed in 2026, lists the following dimensions. Its ATX lengths are examples; ATX depth varies by model.
| Format | Published dimensions | Typical fit | Key clearance check |
|---|---|---|---|
| ATX | 150 mm wide × 86 mm high; example lengths are 140, 160, and 180 mm | Cases with an ATX PSU bay | Check the exact unit depth and clearance around drive cages, radiators, and cables. |
| SFX | 125 × 63.5 × 100 mm | Compact cases with tighter PSU space | Confirm the case supports SFX. In an ATX case, check for a compatible mounting bracket and adequate cable reach. |
| SFX-L | 125 × 63.5 × 130 mm | Compact builds whose cases allow extra PSU length | Confirm the case explicitly supports the additional depth; SFX-L is 30 mm longer than SFX. |
These are Corsair’s published dimensions, not a claim that every manufacturer’s product has identical measurements. Corsair’s PSU form-factor guide notes that ATX length varies.
#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.
Will an SFX power supply fit in an ATX case?
Often, but verify the case and PSU combination. Corsair describes using an adapter bracket to mount an SFX unit at an ATX PSU opening; the SFX mounting holes do not align with the standard ATX opening without the appropriate bracket. The bracket addresses mounting only: it does not make short cables longer or establish that the PSU has enough electrical capacity for your system.
Check cable reach to the motherboard, CPU power socket, graphics card, and drives. A compact PSU’s cables may not reach comfortably across a larger case. Use modular cables approved for the exact PSU model; modular PSU cables are not universally interchangeable. Corsair’s SFX-in-ATX installation guidance covers the bracket and cable-length considerations. For a specific Corsair bracket, consult its product page for the compatible PSU models: SF Series SFX-to-ATX Adapter Bracket 2.0. Do not assume that bracket fits every SFX PSU or case.
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
Can you put an ATX PSU in a mini-ITX case?
Only if that particular case supports an ATX PSU and provides enough room for its depth and nearby components. Mini-ITX describes a motherboard size, not a guaranteed power-supply bay size. Check the case manual or manufacturer compatibility page for supported PSU formats and maximum PSU depth; do not infer fit from the motherboard format or the PSU’s ATX label.
How to choose the right power-supply format
- Check the case first. In its manual or compatibility page, find supported PSU formats and maximum PSU depth.
- If the case requires SFX, choose SFX unless the case manual explicitly allows SFX-L and its additional 30 mm of length clears the available space.
- If the case accepts ATX, ATX is the straightforward option, but compare the exact PSU depth with the case’s available clearance.
- If adapting SFX to an ATX case, confirm a bracket is compatible with both the PSU and case, then check cable reach to every component.
- After confirming physical fit, compare the specific PSU models for system wattage needs, GPU connectors, efficiency, warranty, acoustics, and cable configuration. Form factor alone does not establish a performance advantage.
What the form factor does—and does not—tell you
ATX, SFX, and SFX-L help narrow down physical fit. They do not answer whether a PSU has the right connectors or capacity for your components, whether its cables suit your case, or whether its acoustics and warranty meet your needs. Intel’s official design-guide page identifies separate ATX12V and SFX12V guidelines; it also notes that a newer guide version is available, so its surfaced 2023 revision should not be treated as the latest specification. Intel’s ATX Version 3.0 design-guide page provides standards context, not a guarantee of current product availability.
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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