Overclocking a i5 3750k

Guffmaw

Honorable
Aug 2, 2013
62
0
10,640
So i have a I5 3750K At 3.4ghz default and i wanna overclock to 4.2, just wondering how i would go about this i was following a video and everything was fine my computer WAS so much faster, then i went to load my stress test up my cpu temps and everything see if its fine, then i loaded google and my computer just randomly restarted no errors no black screen just straight up restarted what am i doing wrong? sorry for bad grammar