Most, but not all CPUs can be successfully overclocked, some more so than others (even those that originated on the same wafer during their manufacture). However, it all depends on whether the motherboard (and in particular the revision of the BIOS that is installed) supports overclocking and, if it is, what the limit is. Note that by overclocking, I am also implying underclocking at the same time. The terms overclocking/underclocking mean to run a CPU or other component at a frequency other than its default.
In order to give you a definitive answer, we need to know the make and full model number (including the build revision) of your motherboard. The BIOS revision you have installed will also be useful.