I finally got my system stable, turns out it was the VTT and DQ settings that was making my memory unstable. I learned a lot by reading Freecableguys writeup on VTT

My safest clock for my G0 is 3420Mhz (380 x 9), @ +125mv (or around 1.392V according to cpuz - which drops to 1.360V soon as i start priming). Load temps reach 70°C according to smart guardian and coretemp. memory is running at ~950Mhz w/ 4:5 divider (not 1:1).

i guess this is my final cpu speed, unless i lap the heatsink or IHS.