Claymore is MEGA-monster!

RX480 4G with mod. mem timings = 70-72 sol\sec
Hi,
Can you please explane how you did mod your mem timings in the bios or how it is possible to mod them whitout blowing them up? I try it a cupple time but its more crashing or not starting then working..

do i need to raise them one by one @ the time and always restard them?