how do i disable eist?

i might have got this wrong but cpu-z was reading my fsb multi and voltage as changing under load, so i was advised this could be intels speedstep tech, well i disabled cpu eist function in the bios but the cpu just wont stay at a stable reading so i can overclock....

my mobo is ga-p35-ds3r and cpu is e6750

Edit: solution found,

for anyone interested. you have to disable both cpu eist function and cpu enhanced halt (c1e) in the bios

I would actually recommend using RMClock to control your EIST, and keep your FSB fixed at elevated level. If you get it right you can cut your electricity bill significantly if your system idle most of the time.

i think i disable 4 options on that bios screen from eist downwards - they are all something similar.