The Compaq PDP Power Supply 14-pin connector is a proprietary interface fitted to Compaq PDP-115 power supply units (Compaq part number 165997-001) used in Deskpro EN and EP Small Form Factor desktop systems from the late 1990s to early 2000s. It uses a Molex 39-01-2140 housing — the same 14-position Mini-Fit Jr shell employed by some Acer systems — but carries a signal map that is entirely incompatible with any standard ATX power supply. Notably, the power-on control signal (ON/STBY) is active-HIGH on Compaq PSUs, the inverse of the active-LOW PS_ON# line defined by the Intel ATX Power Supply Design Guide; connecting a standard ATX supply to this board, or vice versa, risks immediate damage to both the supply and the motherboard. Compaq’s Deskpro EN/EP range used at least three distinct proprietary connector variants (14-pin, 20-pin, and 24-pin), of which the 14-pin is specific to Small Form Factor and Net PC models.
| Pin | Name | Description |
|---|---|---|
| 1 | brown | +3,3 V |
| 2 | blue | -12 V |
| 3 | violet | fan off special pin |
| 4 | white | power on-standby |
| 5 | green | +5 V aux |
| 6 | white and red | fan cmd special pin |
| 7 | orange | +12 V |
| 8 | brown | +3,3 V |
| 9 | pink | +3,3 V aux |
| 10 | black | ground |
| 11 | red | +5 V |
| 12 | black | ground |
| 13 | red | +5 V |
| 14 | black | ground |
Signals
- +3.3 V — main 3.3 V supply rail (pins 1 and 8).
- +3.3 V Aux — 3.3 V auxiliary standby rail (pin 9), present whenever mains power is applied.
- -12 V — negative 12 V rail (pin 2), used by legacy serial interfaces.
- +5 V — main 5 V supply rail (pins 11 and 13).
- +5 V Aux — 5 V auxiliary standby rail (pin 5), present whenever mains power is applied.
- +12 V — 12 V supply rail (pin 7).
- Ground — return paths (pins 10, 12, and 14).
- Power On-Standby (ON/STBY) — active-HIGH control signal (pin 4) that commands the PSU to transition from standby to full output; this is the opposite polarity to the active-LOW PS_ON# signal in the Intel ATX specification.
- Fan OFF — special control signal (pin 3) used by the PSU to signal or control fan-off state; this pin has no direct ATX equivalent.
- Fan CMD — fan command signal (pin 6) carrying fan speed or control information; this pin also has no direct ATX equivalent.
Notes
- The physical housing is a Molex 39-01-2140 (14-position Mini-Fit Jr), which is a subset of the same connector family used for ATX 20-pin and 24-pin supplies; the housings are keyed by pin count and are not cross-compatible with ATX supplies.
- The ON/STBY signal is active-HIGH. Attempting to use a standard ATX power supply — whose PS_ON# is active-LOW — on this board without a signal inverter will prevent the system from powering on and may damage the hardware.
- This connector and its pin assignments are shared between the Compaq PDP-115 PSU and the Compaq Deskpro EN/EP Small Form Factor and Net PC system boards; the same 14-pin signal map appears in Compaq service documentation for both product lines.
- Full-tower Deskpro EN/EP systems used a physically different 20-pin Molex 39-01-2200 connector with its own distinct (and still proprietary) signal map.