i have a mother board asus p5b with intel core duo 6400 and vga pixel view 6700 gt . i would like to overlock my machine and i'm asking for someone to help me post a reply .

Gabriel has posted some great tutorials on the subject.Be sure you unserstand what you are doing.I use AMD,and dont know what kind of options you get in BIOS, therefore cant be of much more help.Here is a link to OC the P4 and one how processors work.Maybe you could start there until someone else here shows up with more help.

http://www.hardwaresecrets.com/article/198
http://www.hardwaresecrets.com/article/209

Good Luck :)