Formatting alienware m17x r3

As mentioned above, i nid a simple steps on how to format my alienware m17x r3 without causing any side effects, please?

This is due to my experience in lagging when playing games.. in a few minutes, i will experience lagging for a few seconds..about 30 secs then it came back to normal.. after 5 mins, it will repeat the same thing again.. does any1 know what caused this problem .. in my opinion, i think i nid to format my alienware.. am i doing the right thing? please some1 help me ..