Ivy bridge 3570K freezeup but no BSOD

hey guys, i recently overclocked my 3570K a tiny bit up to 4.2GHz. I ran intel burn test for 10 runs and then prime95. I have my voltage at 1.12 v and level 1 load line cal. The only other change i think i made was to my ram, which i adjusted from 1333 to 1600 to meet its advertised speed. the temperatures are at 34C idle and around 60C when full load.

WHile it had no issues with any of the stress tests, for whatever reason, when I have a few programs open (chrome, winrar, spotify, etc) it will freeze without a BSOD. I'm really confused as to why it will freeze when not under stress, instead of the other way around.

Here are all of my things,

mobo: Asrock z77 Extreme 4
cpu: intel 3570K
cooling: THermaltake water 2.0 Pro
RAM: Corsair Vengeance 4*4GB
Voltage: 1.12V
Bus Speed/Multiplier: 100*42