To be honest...I'm not too sure.
Basically what
should happen, is when your CPU is put under load (such as playing CS:S) the CPU will automatically ramp up in speed, and set itself to 2.53ghz, which isn't dangerous.
I'm sure there should be a way to pump it up to that speed by default, but I'm not too familiar with Intel CPU's of that age group sorry.
Should be a setting in the BIOS somewhere.
What motherboard do you have? Perhaps the manual will tell us
