Power Supply Dell 255W Slim Form Factor FN3MN — 255W AC adapter for Dell slim desktops

The Dell 255W Slim Form Factor power supply is a compact AC adapter designed for slim Dell desktop systems. It delivers up to 255 watts of continuous power to system components, supports the slim-form connector layout used in compatible Dell chassis, and is intended for replacement or upgrade in space-constrained desktop units. The unit is engineered to provide stable voltage and current to the motherboard, storage devices and other internal components to maintain system reliability during typical office and home workloads.

Advantages

This slim 255W adapter occupies minimal internal space while providing sufficient power for typical slim desktop configurations. Its design matches standard slim-form connector placements and mounting points, making installation straightforward in compatible systems. The power supply includes overcurrent and short-circuit protection features to help prevent damage to connected components and to support continuous operation under variable load conditions. The compact form and focused output power help reduce excess heat generation compared with larger, higher-wattage units.

Suitable for

• Replacement of a failed or degraded power supply in compatible Dell slim desktops
• Upgrading or repairing small-form-factor Dell systems that require a 255W AC adapter
• Service and maintenance environments where quick swap of slim power supplies is needed

Key specifications

• Output power: 255 watts continuous
• Form factor: slim desktop power supply designed for space-constrained chassis
• Connector type: slim-form internal power connector compatible with supported Dell motherboards
• Input: AC mains power (standard voltage range for desktop adapters)
• Protection features: overcurrent and short-circuit protection
• Intended use: internal AC adapter for Dell slim desktop systems

How to use

Power down the desktop, disconnect the mains cable and open the chassis according to the manufacturer's service instructions. Remove the failed power supply by disconnecting the internal power connector(s) from the motherboard and any drive or peripheral connectors, then unmount the unit from its bracket or retaining points. Install the replacement 255W slim power supply by securing it in the chassis, reconnecting all internal connectors to their original sockets, and routing cables to avoid interference with fans or other components. Reattach the chassis cover, connect the mains cable, and perform a power-on test to verify normal operation and system stability.

Recommendations

Use this power supply only in systems explicitly listed as compatible by the system manufacturer. Ensure that the system's thermal and power requirements do not exceed the adapter's 255W rating. If adding additional components that increase power draw, verify total system consumption before relying on this unit. For safety, follow electrostatic discharge precautions and the manufacturer's service procedures when installing or replacing the power supply.