guys i have been trying to learn some basics . plz explain to me whatever u can

cpu clock xmb,,,, its gives default and other values , on what should i place and y, same question for CPU clock game
and plz tell me umd iso mode also. that m33 driver and np9660 sony mode

last quetion plz , m using 6.35prob4 , what is the purpose of recovery menu and when we use it