It's not your card that doesn't like overclocking, that curve is just not going to be stable for majority of cards. Do this. Reset to default, bring up the curve Hold shift and drag the whole curve down so that the points on the right are at max frequency of about 1900mhz. Next, select a single point and drag it up to perhaps 2000mhz. I would start off with a voltage of 1.025. So 1.025v @ 2000mhz~. All the points past 1.025v will be the same(this ensures it does not go past the first set point). After that, the 3 or 4 points below 1.025, you'll want to reduce them by 13mhz step each. so it would be 2000 @ 1.025, 1987 @ 1.012, 1970 @ 1.0v and so on. You do not want to go beyond 1.06v~ for most cases as the average frequency will go down due to limited power target. Reducing voltages reduces power usage which will lower temps while keeping average clock speeds up. If above is not stable, maybe try 2ghz at 1.0375v or 1987@ 1.025v etc.