can cpu's lose overclockability? (xp2500m not as good as it used to be)

[bledd]

i used to overclock it to 2.68ghz (185 x 14.5) but now it finds it tough to go anything over 2.4, running at 2.03 v (1.95 actual)

using better ram and better psu now

what else should i try?

on an abit nf7s-v2