8 pin MOLEX 39-29-9082 connector at the motherboard.
8 pin MOLEX 39-01-2080 connector at the cable.
The WTX P3 connector is an optional 8-pin (2×4) Molex Mini-Fit Jr. power connector defined in Intel’s WTX Power Supply Design Guidelines (Version 1.0, February 1999) for the WTX Workstation Technology Extended form factor, introduced in 1998 for mid-range dual-CPU workstations. It supplies the +12V_DIG rail — a dedicated 12 V supply for the WTX Memory D2D (DC-to-DC) converters and processor Voltage Regulator Modules (VRMs) — kept separate from the +12V_IO and +12V_CPU rails carried by P2, P4, and P5. The +12V_DIG rail is regulated to ±5 % (11.40–12.60 V), and optional remote-sense lines on pins 4 and 8 allow the power supply to compensate for cable voltage drop; these sense pins were not populated on some boards (such as the Intel Pentium III/840 Development Kit), where they appear as reserved no-connects.
| Pin | Name | Color | Description |
|---|---|---|---|
| 1 | 12Vdig | white | +12 VDC (Digital) |
| 2 | 12Vdig | white | +12 VDC (Digital) |
| 3 | 12Vdig | white | +12 VDC (Digital) |
| 4 | 12Vdigsen | +12 VDC (Digital Sense) | |
| 5 | com | black | Ground |
| 6 | com | black | Ground |
| 7 | com | black | Ground |
| 8 | 12Vdigsenrtn | 12V (Digital Sense Return) |
Signals
- 12Vdig — +12V_DIG power rail; three pins (1–3) carry current to WTX Memory D2D converters and processor VRMs. Regulated to ±5 % (11.40–12.60 V); maximum output noise 120 mVpp.
- 12Vdigsen — Remote sense for +12V_DIG (pin 4); enables the PSU to measure the voltage at the load point and compensate for cable drop. May be left unconnected (reserved) on boards that do not implement remote sensing.
- com — Ground return; three pins (5–7) provide the current return path for the +12V_DIG supply.
- 12Vdigsenrtn — Remote sense return for +12V_DIG (pin 8); paired with 12Vdigsen to complete the sense circuit. May be left unconnected (reserved) on boards that do not implement remote sensing.
Notes
- P3 is an optional connector; the WTX specification requires only P1 and P2. P3 is fitted when the motherboard includes WTX Memory D2D converters or processor VRMs that draw from the +12V_DIG rail.
- The board-side connector is a Molex 39-29-9082 (Mini-Fit Jr., 2×4, right-angle or vertical). The cable-side connector is a Molex 39-01-2080. The connector is keyed and polarised to prevent incorrect insertion.
- The +12V_DIG rail is a separate supply from +12V_IO (on P2) and +12V_CPU/+12V_CPU2 (on P4/P5), allowing the PSU to regulate each subsystem independently and stay within the 240 VA per-output limit of IEC 60950.
- The WTX form factor was discontinued circa 2001–2008 and was not widely adopted commercially; it was superseded by enhanced ATX derivatives for workstation use.
References
- WTX Power Supply Design Guidelines, Version 1.0 — Intel Corporation, February 1999
- Intel Pentium III Processor/840 Development Kit Manual (Order Number 273333-003) — Intel Corporation, April 2001