Occasional BSOD Issue - OC 36% - Didn't cause issues before  

I built my PC last year and used the Asus AI Overclocking feature to OC my system a safely as possible. It determined that the value of 36% was optimal. I've noticed however in the last few months that I get a BSOD every few weeks, and not while I'm doing anything particularly intensive.

I'm not sure if this is caused by the OC? Any way to find out? What else could be causing this?
this is what I'm getting:



these are the current settings in AI Suite 3



I'm not sure if I need to contact ASUS to try a lower setting to OC or turn it off completely... or if someone here can assist!