eex0bat :
How much do you recommend I should overclock this card?
that all depends on your card.
Install GPU-Z to monitor settings.
While running a benchmark such as Heaven in your native resolution basline you system by noting the MIN/AVG frame rate, as well as Max GPU freq, and Max temp.
Now, while running the benchmark in native resolution, increase your memory freq in 5-10MHz increments until you see artifacts (large blocks of solid colors or bright stars) then drop back until these artifacts disappear. Note this stable Mem Freq, then return to DEFAULT.
Next, increase GPU freq in 5-10MHz increments until you see artifacts (random, multi colored pixel sized dots or colored flashed) then drop back until these artifacts disappear. Note this stable GPU Freq.
Now set your Memory Freq and GPU Freq to the values established above. You may have to drop one (or both) of them down depending on the type of artifact you observe (see above types of artifacts). Drop as necessary to be stable.
Once you are stable re-run the benchmark to see your improvements.