[CentOS] Hot swap CPU

Let's assume that I have a machine with at least 4 CPUs.
In case that one of these fails what are my options.
I mean, could I take that cpu offline and maybe ( I say maybe) I could
change it without taking down the server ?
What is the suggested procedure?
Is this the same procedure no matter what cpu architecture I have
(Itanium, or PPc or whatever )
Thanks in advance for the attention

Zaharioudakis Nikos