you took one SIMM out ? in pentium systems you must have SIMM's in pairs the PC wont function with just one in. take all the SIMMS out and try just the DIMM (168 pins, SIMM 72 pins). do you mean you have a P133 processor, if you do i doubt the new DIMM ram will function and suggest you get some EDO memory. If in doubt get the Ball Pein Hammer out