this has many variants.
#1 you are not exactly clear with your question
#2 the generation of your system matters, if you talk about something 10 years old, and it is overclocked, it will always run at that speed. New systems will only run at overclocked speed if needed.
#3 A stable/proper overclock will NOT ruin your computer, overall it may lessen lifespan, but you will most likely change computer before it dies.