2500k idle multiplier.

Solution
you need to disable speedstep (bios setting usually). that way the cpu won't decrease in speed while idle. this however should not cause lag, the cpu would downclock only when it doesn't need to do anything.
Awesome thank you. I know it shouldn't but occasionally my cpu usage would spike while in bf4 and if i alt tabbed out i would catch my multiplier at x16 instead of x33 or x44 whichever i had it clocked at in msi control center. Its fixed now and is seeing max 60% usage in bf4 now. Thank you.
 
with speedstep on(or auto) it will adjust the cpu frequency based on load. check also the power settings in windows, i think it's possible to set a higher min frequency and then you can leave it on when playing.

the overclock works on the max clock setting, it will tell the cpu that the max clock should be higher than the standard one