Overclocking phenom II 940

hi all.

i have this processor and i want to make a strong overclock on this, then i have some questions.

should i set 15 x 240 to get 3.6 or 18 x 200 to get the same 3.6? whats the diference?

i saw that when i do 15 x 240..the memories also gets overclocked aint this good too?

and about temperature.. when i put it to 3.6Mhz it goes to 57C in idle..too hot i think, and i have a nice cooler from asus, well i live in brazil here is too hot, ill buy a watercooler in about 1 month to have a better temperature.

my motherboard is an Asus M3A78
memories corsair xms ddr2 800Mhz 4x2gb

thanks for the help

thanks for the links man, i've already seen them, but i still dont get the diference between overclocking 15X240 to get 3.6Ghz or 18x 200 to get the same 3.6Ghz.

i saw that when doing 15X 240 memories also gets overcloked, then i wonder isnot it an advantage?