Smile [Q] LG P690 Overclock and Chainfire 3D

Hi, i saw this post in the forum So i wanted to ask about the Overclock with LG P690, the problem is - when set the Max CPU Frequency to 921Mhz or more after a few seconds the phone reboots but it works perfectly under 921Mhz(902Mhz Maximum!) some said that they overclocked it to 940Mhz(or even 1Ghz+) can you tell me how to do that? Please! And about Chainfire 3D wich settings to use because i don't understand it clearly? Thanks!