6 pin ATX AUX power connector at the cable
The Dell ATX Aux connector is a 6-pin supplementary power header found on Dell Pentium II and Pentium III era desktop systems, including the OptiPlex GX1, GX110, Dimension 4100, and Precision 410. It carries three ground returns and three +3.3 V lines, providing additional current capacity for the system board beyond what the main power connector delivers. Dell’s power supply design of this era deviated unilaterally from the Intel ATX 2.x Power Supply Design Guide, using physically identical Molex Mini-Fit Jr housings but with non-standard pin assignments; connecting a standard ATX supply in place of a Dell proprietary supply risks immediate damage to both the power supply and the motherboard. Dell returned to the standard ATX pinout with its Pentium 4-generation systems.
| Pin | Name | Color | Description |
|---|---|---|---|
| 1 | COM | black | Ground |
| 2 | COM | black | Ground |
| 3 | COM | black | Ground |
| 4 | 3.3V | blue/white | +3.3 VDC |
| 5 | 3.3V | blue/white | +3.3 VDC |
| 6 | 3.3V | blue/white | +3.3 VDC |
Notes
- This auxiliary connector supplements the main proprietary 20-pin Dell power connector present on the same systems; both must be connected for correct operation.
- The physical housing is a Molex Mini-Fit Jr 6-position connector, visually similar to the standard ATX 2.x aux connector, but the signal assignments on the accompanying main connector differ substantially from the ATX specification.
- Dell Pentium II/III proprietary power supplies are not interchangeable with standard ATX supplies. Cross-connecting can place 12 V on signal lines that expect 3.3 V or 5 V, causing immediate hardware damage.
- Dell standardised on the ATX pinout for Pentium 4-generation desktops; the Dimension 8100 (circa 2001) was the last Dell desktop platform to require a fully non-standard proprietary power supply.
- Wire colours shown are typical for Dell OEM harnesses of this era; individual batches may vary.
Signals
- COM — Ground return (0 V); three separate lines reduce impedance and carry the return current for the 3.3 V rails.
- 3.3V — +3.3 VDC supply rail; three lines in parallel increase current capacity for the system board logic.
References
- Compaq Deskpro EN 6550/6400 Service & Reference Manual (Doc 133756-004) — Connector Pin Assignments — Compaq Computer Corporation; documents OEM proprietary power-connector pinouts contemporaneous with Dell’s proprietary ATX-physical variant, including the active-HIGH control signalling that distinguishes these OEM designs from standard ATX.