did you increase the voltage in EVGA precision x (also known as the power target), if not then do so, set it well above what you think you might need. then just lower the voltages after the card is at full load so you can see what kind of percentage you need.
Yes have set to max sliders for power, and tweaked mv as well, will see if memory on card is samsung or not, read about evga using cheaper brand that doesnt oc well at all..