You could probably go into the BIOS and back down the voltage before you hurt the CPU, but just to be safe, reset the BIOS back to factory settings. (Remove/reinstall the battery with the power cord removed, if you can't find the reset jumper)
Then when you turn the computer back on, it should be factory speed and voltage.
Then go back and overclock with the understanding that your motherboard will automatically increase voltage as you increase speed. In order to avoid your vcore going too high, you must lock the voltage down and set it manually, or use a negative offset so that the voltage is x.xxx lower than the automatic voltage for a given speed.
I prefer the offset method so that my voltage goes down at idle.