In most cases, No. Youll have to see if there are jumpers on the motherboard or settings in the BIOS to change the CPU bus frequency and/or the multiplier if your CPU will allow it.
What you need to do is open the computer and see if you can find a model number on the motherboard. Sometimes there will be a sticker on the end expansion slot, ISA or PCI, or it may be printed on the motherboard. IF you can find some numbers on the board, put them into a search engine and see if it will give you a link to the manufacturers website. Once you know who makes the board you should be able to obtain a manual for the specific board and see if there are any options for changing the CPU speed.