Excuse me for being such a noob but how do i know if my system clock is 240mhz or 250mhz?
The stock system clock is 200MHz. The CPU, hypertransport links, memory controller/north bridge, and system memory use 'multipliers' to set their speeds based upon the system clock.
When over-clocking you may adjust those multipliers to maintain stability and increase performance. You may look at it like this:
At stock DDR3 1333 operates at 6.67x200MHz. If you raise the system clock to 250MHz, in order to operate your memory within spec you may drop the memory multiplier (or 'ratio') one notch down to 533
5.33x250MHz = 1333MHz ---- your memory is operating at spec.
The PhII 840 Propus quad at stock is 16x200MHz or 3.2GHz (and you wish to run the system clock at 250MHz). For a 'noob' you may simply drop the cpu multiplier to '14' with the system clock at 250MHz. Congratulations. You are now running at 3.5GHz.
The PhII 840 will easily run 15x250MHz (as will the X3 Rana). It may stress that AsRock 'LE' motherboard a bit so DDR3 1600 will help you, here.
At stock it is 8.00x200MHz. Raise the system clock to 240MHz and drop the ratio to 667 (and 6.667x240MHz = ???
And your PhII 840 cpu at 15x240MHz should feel quite 'snappy' -- past that you will most likely need some after-market cooling to keep things smooth and easy