What is Quad Pumped Bus (QPB)? Is it just technology which multiplies FSB by 4 or what? Because I don't know if when I increase FSB it will affect QPB.
The Front Side Bus links your CPU to your memory. Since they are linked, they are synchronized. This is why it affects your memory if you increase the FSB. If you are increasing your FSB and have no idea why it affects your memory, I will stop you right there.
You need to read an overclocker guide. Overclockers.com usually have good ones. Don't be fooled by the date on them. Motherboard architecture hasn't significantly changed in a decade.
edit: QPB is just the processor transferring data 4 times a clock cycle. The Pentium 4'ss and Core 2'ss used it.
Edit: Here is are some fun pictures for ya.