From your original post I thought you had an ATI card.
To overclock Nvidia cards you need to adjust the power limit.
Set it to 112% or max allowable.`Then adjust the fan profile as aggressive as possible to keep it cool but with bearable fan noise.
The cooler you keep the card the higher it will boost.
My fan profile is a 45 degree angle. At 40c the fan runs 40%, 50c the fan runs 50%, 60 degrees 60% etc.....
I run a Asus 1070 Dual for Folding which pegs the card at 100% load. Some work units are better optimized and push the card more which results in a lower boost rate.
The new Boost2 ,along with drivers and bios settings vary the clock rate depending on power draw,temperature, and core utilization.
Keeping the card cooler will give you higher boost rates.
Mine will boost to 2012mhz, but as it warms up it will drop to an average of 1962 on most work units. And as low as 1927 on others.
You will just have to experiment and see what works best for your card, and case cooling( getting the hot air out of the case) is also very important.
The cooler you keep the card the higher it will boost.