If you get it with 2 different PSU's, then I would suggest you get a meter and measure it directly on the motherboard (carefully - don't short anything out). If the meter has thin probe tips you can go straight into the back shell of the ATX connector. Most m/b manuals show the ATX connector pin assignments. If yours doesn't, just holler
If after measuring it, your 3.3V rail
really is that low and it isn't a problem with the m/b monitoring circuit or monitoring software, then something is fubar in your system - at which point you need to start a troubleshooting series of steps to find the culprit.
As far as the 12V rail - while 11.67 isn't optimal, it isn't really bad (only about 3% off), especially when considering most P4's m/bs use the 12V for the Vcore circuit.