I have 1200Mhz 950mv
2000Mhz 1000mv

For Zec the mem speed dont affect soo no need to preasure them, the core i put on 1200Mhz because the power draw, i have to pay the power usage and i have the rig in my living room, at 1200MHz 950mv i get a solid 63Degres at around 30%fan, low noise and low temps, at 1300Mhz i have to up the vcore to 1130mv and to stay at same temp the fans go up to 60% and made louder fan noise and draw more power... im getting 165Hs at this setting per card, at 1300 i get 180Hs