any [linear] voltage regulator needs a load for it to regulate correctly.
if you are testing it open ended with only a multimeter, it can show any random voltage, put a load on it and it will stabilise.
if you look at the schematic http://www.megamanual.com/ms2/v3pcb_6.gif
without a cpu in the socket, the regulator is operating open ended.
generally you wont get a stable voltage in this state.
ie try a back to back test any 1-10k resistor across the S5 and SG holes near the DB9 and it will show you a stable voltage.