What ram speed and timings are you using? I has such problems with my rams XMP @ 3200. In the end I lowered ram speed to 2666 with 13, 14, 14, 35. 1T timings. Now i'm at 4.4Ghz on the cpu, AIDA64 stable for 5 hrs with only 1.130v on the core. I just lowered the vcore to 1.120v and am running another AIDA64 system stability test. Load temps are great too at 50-60c.
One thing I've found is that for temps 4.4 seems a sweet spot. The temps go up considerably beyond this. Hardly worth it for a couple of hundred Mhz methinks.
I'm gonna keep dropping the core voltage by 0.010 until it becomes unstable then go back up to the last stable setting and call it a day.
Incidently, I had it boot at 4.8Ghz with only 1.250v but the temps were up in the 70's when I started the test so I just ended it after a few seconds. I'm not interested in pushing the chip that much anyway. 4.4 at the volts i'm using now and super low temps are perfect for what I want.