SFX vs ATX Power Supply: Fit, Wattage, and Cooling

The Lian Li SP750 V2 is a premium SFX power supply designed specifically for small-form-factor PC builders who refuse to compromise on power delivery or efficiency. This unit sits at the sweet spot between compact size and legitimate 750W capacity, making it ideal for ITX enthusiasts building high-performance gaming or content creation machines in tight spaces.

What truly sets this unit apart is its future-ready ATX 3.1 certification and native 12V-2x6 connector support. This means you can power current and next-generation high-end graphics cards without relying on adapter cables, reducing potential power delivery issues and simplifying your build. The fully modular cabling design gives you complete control over which cables actually enter your case, resulting in dramatically cleaner builds and better airflow in already-tight SFX enclosures.

Build quality is solid throughout. The premium 92mm FDB (Fluid Dynamic Bearing) fan operates with barely audible noise levels, even under load. The upgraded 5VSB standby rail now delivers 3A instead of 2.5A, better supporting the growing demands of USB hubs and always-on peripherals. The unit fits the official 63.5mm SFX specification perfectly, ensuring broad case compatibility without any fitment surprises.

The main limitation is obvious: SFX form factor means this is strictly for compact builds. If you're planning a standard ATX case, you need a full-size PSU. Additionally, while 750W is solid for most gaming systems, extreme high-end configurations pairing flagship CPUs with flagship GPUs might benefit from additional headroom. These are honest trade-offs of the form factor, not design flaws.

The 10-year warranty reinforces Lian Li's confidence in this unit's reliability. Real-world user feedback consistently highlights stable power delivery, silent operation, and excellent durability even during power surges. For SFX builders, this is a no-compromise choice that justifies its premium positioning.

Power Output: 750 watts continuous
Form Factor: SFX (4.92 x 3.94 x 2.5 inches, 3.9 pounds)
Efficiency: 80 Plus Gold certified
Cooling: Single 92mm FDB bearing fan
Input Voltage: 110-120V AC
Connectors: 20+4 Pin ATX, PCI Express 12V-2x6 native, fully modular cables
Certification: ATX 3.1 compliant with transient spike protection
Warranty: 10 years hardware protection
Model: SP750G.B

Who Should Buy: SFX PC builders, ITX enthusiasts, compact gaming system builders, content creators in space-constrained environments, anyone prioritizing silent operation and future-proof power delivery.

Who Should Skip: Budget builders looking for the cheapest option, users with standard ATX cases, anyone building extreme high-end systems regularly pushing 900+ watts.

Key Considerations: Verify your case supports SFX PSUs before purchasing. The native 12V-2x6 connector is a major future-proofing advantage for PCIe Gen 5 graphics cards. Fully modular design means cable management is your responsibility, but offers maximum flexibility. The quiet 92mm fan makes this excellent for noise-sensitive builds, such as streaming PCs or office workstations.

Real-World Performance: Users report stable power delivery under load, excellent handling of power surges in unstable electrical environments, and truly silent fan operation in typical gaming scenarios. The compact form factor fits snugly in Lian Li B4 and similar SFX cases without any fitment issues.

Choosing between SFX and ATX often comes down to one question: can a smaller supply actually keep up with a full-size unit? The ROG Loki SFX-L 750W Platinum answers yes. It packs 750W into a 4.9 x 4.9 x 2.5 inch SFX footprint, matching wattage tiers typically reserved for ATX builds while fitting cases where ATX simply won't go. The 80 Plus Platinum rating pushes efficiency to 92%, so the thermal and power tradeoffs that usually come with downsizing are minimized. A 120mm fan with Lambda A certification keeps noise under 25dB, addressing the common concern that smaller cases run hotter and louder. The 16-pin PCIe cable rated for 600W and ATX 3.0 and PCIe 5.0 readiness mean this isn't a compromise pick, it's built for current and next-gen GPUs. Full modularity also helps where SFX cases offer little room for excess cabling. For anyone weighing SFX against ATX purely on capability, this unit closes most of the gap.

Power Output: 750W with full modularity
Form Factor: SFX-L
Efficiency Rating: 80 Plus Platinum (up to 92% efficient)
Cooling: 120mm PWM axial-tech fan
Noise Level: Lambda A certified, below 25dB
Connectors: 16-pin PCIe cable, fully modular design
Compatibility: ATX 3.0, PCIe 5.0 ready
Dimensions: 4.9 x 4.9 x 2.5 inches
Weight: 4 pounds
Input Voltage: 100-240V AC
Warranty: 10 years core operation, 3 years RGB LED

Buy this if you're building a small form factor gaming PC and want ATX-level wattage and GPU support without stepping up to a bigger case. It suits ITX builders planning high-end graphics cards. Skip it if your case is standard ATX or mid-tower, since the SFX-L form factor won't install, or if your build's power needs are modest enough that a lower-wattage SFX unit would do.

This article is about matching fit, wattage, and cooling to the right case, and the ST30SF V2 is one of the few supplies that actually bridges both standards. It's built as an SFX unit but ships with an ATX mounting bracket, letting it drop into standard ATX cases as easily as SFX ones. That flexibility matters if you're undecided between form factors or building a system that might change cases down the line. Wattage is capped at 300W, which keeps cooling demands modest, a single 92mm fan is enough to manage heat at this output level. The 80 Plus Bronze rating and single +12V rail keep the design straightforward rather than high-performance, which suits lighter builds rather than GPU-heavy ones. At 3.94 x 4.92 x 2.5 inches, it's compact enough for tight cases but rated for continuous operation at 40°C, so it holds up under sustained use. For a comparison centered on fit and form factor compatibility, this is the clearest example of a supply that doesn't force a choice.

Electrical: 300W continuous at 40°C, 80+ Bronze efficiency (82-85% at 20-100% load), single +12V rail, input 115-240V AC

Physical: SFX and ATX compatible (bracket included), dimensions 3.94 x 4.92 x 2.5 inches, 1x 92mm fan, weight optimized for portability

Connectors: ATX connector via bracket, SFX connectors standard, supports modern 12V high-current delivery

Support: 3-year parts and labor warranty, model SST-ST30SF-V2-USA, manufactured by SilverStone Technology

Buy this if you want a single power supply that works in either an SFX or ATX case, especially for budget builds, HTPCs, or office PCs with modest power needs. Skip it if you're running a high-end GPU or power-hungry components, since 300W and Bronze efficiency won't keep pace, and skip it if dual-fan cooling redundancy is a priority.

Fit and wattage usually trade off against each other in SFX builds, but the GOLDEN FIELD 550W works to close that gap. It's built specifically for SFX and mini-ITX cases at 4.92 x 3.94 x 2.52 inches, yet delivers 550W with 80 Plus Platinum efficiency rated at 93% at 50% load. For cooling, a single 9cm PWM fan is paired with a design that emphasizes component quality, 100% Japanese capacitors, a pure copper transformer, and tinned copper cables, so the unit manages heat without needing bigger or multiple fans. ATX 3.1 and PCIe 5.1 support along with handling 300% instantaneous power spikes make this relevant for builders pairing compact cases with demanding GPUs. Full modularity also directly helps airflow in SFX cases where cable clutter restricts cooling. The tradeoff is that this 550W model skips the 12V-2x6 cable, so GPU power delivery planning matters if you're aiming for top-tier graphics cards in a small case.

Power Output: 550W continuous (45.5A on 12V rail)
Efficiency: 80 Plus Platinum, 93% at 50% load (115V)
Form Factor: SFX (100 x 125 x 64mm)
Connectors: 20+4 Pin ATX, PCIe, Native 12V-2x6
Cooling: Single 9cm PWM fan with temperature control
Weight: 1.9 pounds
Standards: ATX 3.1, PCIe 5.1 compatible
Warranty: 10 years

Protection Features: OPP (overpowerload), OVP (overvoltage), SCP (short circuit), SIP (surge input), UVP (undervoltage), OTP (overtemperature)
Cable Type: Fully modular with tinned copper cores
Internal Design: 100% Japanese capacitors, pure copper transformer, LLC plus DC-DC topology with Active PFC and SR synchronous rectification

When comparing SFX against ATX, the real tradeoff is usually size versus capacity, and the V750 SFX Gold narrows that gap. It fits the SFX form factor exclusively, so it will not work in a case expecting ATX dimensions, but for builders who have already committed to a small chassis, it delivers 750W, which covers most gaming and workstation setups that would otherwise seem to require a larger ATX supply. The PCIe 5.1 connector with a 90-degree design and ATX 3.1 cabling delivering up to 450W to the GPU shows this unit is built to modern power standards despite its compact size. 80 Plus Gold efficiency keeps thermals in check, which matters in SFX cases where airflow is already tighter than in ATX towers. The full-bridge LLC converter and EMI-inhibited amorphous metal core support stable delivery under load, and the single FDB fan carries Cybenetics Gold noise certification for quieter operation. For an SFX-only build that still needs serious output, this is a strong case for not needing ATX at all.

Power Output: 750W continuous
Form Factor: SFX (3.94 x 4.92 x 2.5 inches, 3.1 pounds)
Efficiency Rating: 80 Plus Gold, Cybenetics Gold certified
Design: Fully modular with customized short cables
Connectors: 24-pin ATX, EPS 8-pin, PCIe 5.1 12VHPWR (90-degree), PCIe 6+2 pin, SATA, Molex
Cooling: Single FDB fan with A-noise rating
Input Voltage: 100-240V AC
Warranty: 10 years manufacturer
Compatibility: Mini-ITX, SFF, and standard ATX cases with included mounting bracket

Choose this if your case is strictly SFX and you were worried that meant settling for less power than ATX offers. It handles most gaming and workstation builds comfortably. Skip it if your case supports ATX and you plan to run a top-tier graphics card, since 750W may be tight once total system draw is calculated, or if you specifically need the universal ATX form factor for future case changes.

Shopping between SFX and ATX usually comes down to one question: can a smaller unit still deliver real wattage and clean cooling without forcing a case upgrade. The V850 SFX Gold answers that directly. It uses the compact SFX form factor but outputs a full 850W, closing the gap that normally pushes builders toward bulkier ATX units just to get headroom for a strong GPU. The 12V-2x6 connector supports modern PCIe power delivery, so you are not sacrificing GPU compatibility for the smaller footprint. 80 Plus Gold efficiency and Cybenetics Gold certification mean less wasted heat inside a case that already has less room to dissipate it than an ATX tower. Japanese capacitors and a full-bridge LLC converter back up voltage stability under load, which matters more in cramped airflow conditions. If your case accepts either form factor, this is the SFX pick that competes with ATX on power while staying SFX on size.

Power Output: 850W rated capacity with 16A current rating per rail. Supports up to 600W delivery to GPU via 12V-2x6 connector with ATX 3.1 standard compliance.

Efficiency and Certification: 80 Plus Gold rated for high conversion efficiency. Independently certified by Cybenetics as Gold tier with Noise rating A minus for quiet operation.

Form Factor and Dimensions: SFX compact form factor measuring 3.94 x 4.92 x 2.5 inches. Weighs only 3.1 pounds, making it ideal for portable and space-constrained builds. Includes ATX compatibility bracket for expanded case support.

Connectors and Cabling: Fully modular design with 12V-2x6, ATX, EPS, PCI Express, and SATA connectors. Features 16AWG high-efficiency PCIe cables with 90-degree durable connector design for improved electrical safety.

Input Specifications: Accepts 100-240 volts AC input with automatic voltage detection. Single 140mm fluid-dynamic bearing (FDB) fan provides efficient, low-noise cooling.

Warranty and Support: 10-year manufacturer warranty with 10-year spare parts availability through EU channels, ensuring long-term support and serviceability.

Buy this if you are deciding between SFX and ATX because your case can fit either, and you want SFX-level space savings without giving up ATX-level wattage for a strong GPU. Skip it if your case only accepts full ATX, or if a single 140mm fan's cooling capacity concerns you in a poorly ventilated enclosure. Also skip it if you need more than 850W of headroom for heavy multi-GPU or expansion setups.

The CORSAIR SF750 is a premium SFX power supply designed for builders prioritizing efficiency, reliability, and compact form factors. It targets enthusiasts running high-performance small-form-factor PCs, content creators who need stable power in tight spaces, and anyone upgrading from an older PSU who values long-term reliability and efficiency.

What sets this unit apart is its 80 PLUS Platinum certification combined with ATX 3.1 compliance and PCIe 5.1 readiness. The 750W capacity handles demanding workloads smoothly, while the fully modular design with Type-5 Micro-Fit connectors keeps cable clutter minimal. The 92mm PWM fan with Zero RPM Mode operates silently under partial loads, making this a genuinely quiet option for noise-sensitive setups.

Build quality is impressive throughout. Japanese 105°C rated capacitors indicate attention to component sourcing, and the fluid dynamic bearing fan suggests longevity. The 2.1-pound unit measures just 4.92 x 3.94 x 2.5 inches, making it substantially smaller than standard ATX supplies while the included SFX-to-ATX bracket ensures compatibility with larger cases. The 7-year warranty backs CORSAIR's confidence in durability.

The main drawback is cost. Platinum efficiency commands a premium, and SFX form factors carry inherent compatibility limitations with older or specialized case designs. Additionally, 750W sits at the threshold for extreme multi-GPU builds, though it handles single-GPU gaming and workstation setups comfortably.

The CORSAIR SF750 is an excellent choice for builders who value efficiency, quiet operation, and compact design. If you're building a high-end small-form-factor PC and can justify the investment, this supply delivers reliability and performance that justifies its price.

Power and Efficiency: 750W output, 80 PLUS Platinum rated, supports 110-120V AC input

Form Factor and Connectors: SFX form factor (4.92 x 3.94 x 2.5 inches), fully modular with Type-5 Micro-Fit connectors, 24-pin system bus connector, includes SFX-to-ATX bracket

Cooling: Single 92mm PWM-controlled fan with fluid dynamic bearing, Zero RPM Mode for silent operation at low loads

Components: Japanese 105°C rated capacitors, 9A maximum current rating

Warranty: 7-year manufacturer warranty, model CP-9020284-NA

Ideal For: Small-form-factor PC builders, silent PC enthusiasts, content creators in compact spaces, high-performance workstation builders, anyone upgrading from an older PSU who values efficiency and longevity

Consider Alternatives If: You have a strict budget and efficiency is secondary, you need more than 750W for multi-GPU workloads, your case is incompatible with SFX form factors

Best For: Gaming PCs with RTX 4070-4080 range GPUs, professional workstations under 750W load, streaming and content creation setups, ITX and small ATX builds where space and heat matter

The Apevia SFX-AP500W is a purpose-built power supply for small form factor PC enthusiasts and budget builders. This 500W unit targets Mini ITX and Micro ATX systems where space is at a premium, delivering steady power output in a chassis measuring just 4.92 x 3.94 x 2.5 inches. Whether you are building a compact gaming rig, a living room HTPC, or upgrading an aging small form factor system, this PSU addresses the specific power delivery needs of constrained spaces.

The standout feature is its adaptive connector system. The 8pin CPU connector, 8pin PCIe connector, and 20+4pin motherboard connector each split into modular configurations (4+4, 6+2, and 20+4 respectively) by simple manipulation. This flexibility eliminates the frustration of incompatible connectors and adapter cables, making the PSU compatible with a wide range of older and newer motherboards. The unit includes 11 total connectors covering SATA, Molex, PCIe, and main power needs, providing ample options for SSDs, HDDs, fans, and accessories.

Build quality reflects the budget positioning. The 80mm auto thermal-sensing fan keeps noise levels reasonable under typical loads by adjusting fan speed based on internal temperature. The non-modular cable design is a practical necessity for the compact form factor but means excess cables require careful management in tight cases. Sleeved cables do help with aesthetics and routing in visible small form factor builds. The PSU includes standard protections against overload, short circuit, and thermal issues, backed by a 1-year warranty.

The main limitation is 500W output. While sufficient for integrated graphics systems and mainstream components, this PSU cannot support high-end discrete GPUs like RTX 3070 or higher. Additionally, first-time builders should note the PSU requires all motherboard connectors to be seated before the unit powers on, a design choice that can cause confusion if cables are left disconnected during initial troubleshooting.

The Apevia SFX-AP500W is a sensible pick for compact PC builds prioritizing space efficiency and affordability over cutting-edge power headroom. Its adaptive connectors and thermal fan justify the modest cost, making it the practical workhorse for small form factor enthusiasts and value-conscious builders alike.

Power Output: 500W continuous
Form Factor: SFX, Mini ITX, Micro ATX compatible
Dimensions: 4.92 x 3.94 x 2.5 inches (L x W x H)
Cooling: 1 x 80mm auto thermal-sensing fan
Input Voltage: 115V AC
Total Connectors: 11 (1 x 20+4pin main, 1 x 8pin CPU with 4+4 split, 1 x 8pin PCIe with 6+2 split, 3 x SATA, 2 x 4pin Molex)
Cable Type: Non-modular with sleeved cables
Warranty: 1 year
Protections: Overload, short circuit, and thermal protection

Ideal For: Budget-conscious builders creating Mini ITX or Micro ATX systems, enthusiasts upgrading compact PCs, HTPC builders, retro computing projects, and anyone prioritizing space efficiency over maximum power output.

Not Recommended For: High-performance gaming builds with enthusiast-class GPUs, power-hungry workstations, or users requiring more than 500W for their specific component list. Consider a higher wattage PSU if your system includes RTX 3070, RTX 4070 or equivalent high-end components.

Best Use Cases: Office PCs, productivity builds, retro gaming systems, compact streaming setups, budget gaming rigs with mid-range GPUs, and small form factor entertainment systems.

For builders weighing SFX versus ATX purely on fit, the Apevia ITX-PFC500W makes the case for going even smaller. It is built for Mini ITX and FLEX ATX cases, form factors that are more compact than standard SFX in many enclosures, so it suits builds where even an SFX unit might be oversized. At 500W, it is not chasing ATX-level wattage, but for modest ITX systems with mainstream CPUs and GPUs, that ceiling is enough, and the fully modular design lets you skip unused cables entirely, which matters more as case volume shrinks. Active PFC rated for 90-264V means the unit adapts to different power grids without manual switching, a practical detail for builders assembling systems across different regions. The protection array covers OVP, OLP, OCP, OTP, and SCP, and connector splits accommodate both older and newer motherboards. This is less about matching ATX power and more about fitting where ATX, and even some SFX units, physically cannot.

Power Output: 500W total
Form Factor: Mini-ITX / FLEX ATX
Connectors: 1x 20+4pin main, 1x 8pin 12V (splittable 4+4), 2x 6+2 PCIe, 2x SATA, 2x 4pin Molex
Voltage Rails: +3.3V at 12A, +5V at 14A, +12V at 33A, -12V at 0.3A, +5Vsb at 2.5A
Cooling: 40mm double ball bearing fan with forced air ventilation
Protection: OVP, OLP, OCP, OTP, SCP
Dimensions: 160mm x 73.66mm x 35.5mm (6.3 x 2.9 x 1.4 inches)
PFC Type: Active, full range 90-264V

If you're trying to decide between SFX and ATX for a small build, the APEVIA SFX-AP400W makes that choice easy by committing fully to the compact route. At 125mm x 100mm x 63.5mm, it's built around the SFX form factor's core promise: fitting into cases where a standard ATX unit simply won't go, while also flexing to Micro and Mini ATX chassis. On wattage, 400W puts it firmly in the low-power category, suited to systems that aren't running demanding graphics cards. Cooling comes from a single 8cm fan with auto thermal sensing, so output scales with load rather than running at a fixed speed, and fully sleeved cables keep the inside of a small, visible case tidy. Connector coverage includes PCIe, SATA, Molex, and floppy, which matters for older boards and drives you might be pairing with a small chassis. For anyone whose SFX vs ATX decision comes down to fit over headroom, this covers the fit side well.

Power Output: 400W total, with 28A on the 12V rail, 12A on 3.3V and 5V rails, 2.5A on standby, 0.3A on negative 12V rail.

Form Factor: SFX, compatible with Mini ITX and Micro ATX form factors. Compact dimensions of 5 x 4 x 2.5 inches fit tight chassis configurations.

Connectors: Single 20+4 pin motherboard connector, 4-pin 12V (P4), 6/8-pin PCIe, 2x SATA, 2x Molex, 1x Floppy. All cables are fully sleeved.

Cooling: Single 80mm automatically thermal sensing fan with temperature-dependent operation. Non-modular fixed cable design.

Input: 100-230V AC input voltage range. Standard power switch included.

Warranty: 1 year manufacturer warranty with responsive support team.

Good for small form factor and microATX builders who need a physically compact PSU and whose power draw stays modest, including system restorers working with legacy hardware. Skip it if your SFX vs ATX comparison is really about wattage headroom for gaming or high-end GPUs, since 400W and budget components won't support that. Also skip it if you need modular cabling for tight SFX cases.