-Firstly this is going to sound a little wierd, but have you tried re-seating the ram modules?
-Were you mindful of static when building your PC (unlikely but possible)?
-What temps are you getting? any abnormalities? if so check the seating of the cpu as well.
-Did you do a fresh windows installation with the latest drivers after you installed your new stuff?
-Check for bent CPU pins if you haven't already done so
-As a last resort strip the system down to bare necessity i.e only OS drive, CPU, RAM, input. Nothing else, as your CPU has integrated GPU.
You should not have to raise the voltage of the ram just for it to run at its rated specs, if it does then it wouldnt have passed QC, not to mention that it was working fine in your previous PC.
Also please do not try and oc more than one component at a time, if you want to OC the CPU, then dont attempt to oc anything else until you have found a stable OC for the CPU.