The Optiplex 5050 SFF uses a proprietary 6-pin power connector instead of the standard 24-pin ATX connector found on most motherboards. The pins themselves are standard ATX size; only the housing and pinout differ. This guide documents how to wire a standard ATX PSU to power the board using this connector.

Note: This was verified on a Dell Optiplex 5050 SFF specifically. Dell has a history of reusing connector housings with different pinouts across models and revisions, so do not assume this applies to any other Optiplex variant without independent verification. All voltages were measured live with a multimeter using the COM pins as a ground reference.

The pinout for the 6-pin Dell connector is as follows:

Pin	Function	Voltage	ATX Equivalent
1	12V	12V	12V (White)
2	12V SB	12V	See notes
3	PWR_OK	~5V	PWR_OK (Grey)
4	COM	0V	COM (Black)
5	PS_ON	~5V idle, 0V on	PS_ON (Green)
6	COM	0V	COM (Black)

The main complication in this conversion is the standby rail. Dell uses a 12V standby rail on this connector instead of the industry-standard 5VSB. This rail keeps the board partially powered when the system is off, supplying the RTC, wake-on-LAN circuitry, and power button logic. A standard ATX PSU has no 12V standby rail, only a 5VSB rail, so there are two ways to handle this.

The simpler approach is to wire the 12VSB pin to a spare 12V rail from the ATX connector, or leave it unwired entirely. Wiring it to a spare 12V rail is preferable so the board sees two 12V rails as Dell intended. Do not connect 5V to the 12VSB pin without a boost converter, as this will damage the board.

Without a proper standby rail, the board has no power when the system is off and cannot listen for a power button press. This means PS_ON must be permanently pulled to ground so the PSU brings its main rails up as soon as mains power is applied. The cleanest way to do this is to bridge PS_ON to one of the COM pins inside the connector itself using a short jumper wire:

1. Remove the pin from one of the existing COM wires pulled from the ATX connector.
2. Crimp a new pin onto that COM wire along with one end of a short jumper wire, so both share the same pin.
3. Insert this into one of the COM positions in the Dell connector.
4. Remove the pin from the PS_ON wire pulled from the ATX connector.
5. Crimp a new pin onto the PS_ON wire along with the other end of the jumper wire.
6. Insert this into the PS_ON position in the Dell connector.

This bridges COM and PS_ON inside the connector with no external splicing. It is functionally the same as the paperclip PSU bypass trick: PS_ON pulled to ground tells the PSU to bring the main rails up. The tradeoff is that the PSU fan runs continuously, since the PSU never enters a standby state.

The alternative is to use a boost converter to step the ATX 5VSB rail up to 12V and feed that into the 12VSB pin instead. With a proper standby rail present, PS_ON does not need to be bridged and the power button works normally. The PSU can also enter a low-power standby state, so the fan will not run continuously.

One practical note on the connector itself: the Dell pins are significantly harder to depin than standard ATX pins. The locking tabs are small and require considerable force to depress fully. Work slowly with a proper depinning tool set and do not force anything at an angle, as the pins bend easily. The ATX side is much more forgiving by comparison.

Two 12V pins are used in this implementation to split the load as Dell originally intended, rather than running all current through a single pin.

For the full write-up, including wiring diagrams and verification methodology, see the GitLab repository.