Alright lets try this Please read carefully:
MSI Radeon HD 7770 easily crashes/ very unstable - Radeon - Graphics & Displays
Now since you have oc ram and a video card, lets attempt to underclock your memory back down to 1600mhz or even 1333mhz.
Next find a way to underclock your gpu's speed to normal manufacturer specs if any.
I have a bad feeling the reason why you and many others may have this problem because everything is abit to OC'd.
If after all of this does not work, your last option is contacting msi personally.
Also I recommend you let them see this thread if they attempt to give you the run around of not helping you.
And how do you underclock both the RAM and gpu? I cant find any google results