thing is its luck of the draw and a great oc say under heaven may crash under anything else youy need to run several programs/ games / benches to find the best all day all a round clocks
I use 3 profiles one is 24/7 best overclock runs all I got one profile is maxed out for just heaven or firestrike but will have issue with other things I run . and so on
thing is you got to adjust to the best overclock that don't crash or have issue with all you run under it . some times a card may not do anything more over then what it came out of the box ..
pretty sure your card boosted far higher then what asus speced it to do
like say my card was speced for 1250 but in real life out of the box it does 1375 - I'm gurenteed the card will do 1250 but box stock factory it doing 1375 , see ??? .
big thing is hittin the voltage limits set on the card bios
look at this gpu-z . see how its banging the power limits to try to hold the oc they put on that card ? the more color you get in that field the more its suffering to try to hold the clocks set [throttling occurs ]
http://imgur.com/YDTq3pV
may look up threads as this one to add to help ?
http://www.tomshardware.com/answers/id-2823032/overclocking-asus-strix-gtx-960.html
''Please remember that every video card is different and the overclocks we achieve here are not necessarily what you will be able to achieve''
https://www.hardocp.com/article/2015/03/23/asus_strix_gtx_960_directcu_ii_oc_video_card_review/3
like these guys point out
''We'll have more on this in our full retail card reviews very soon as it will be one of the key differentiator between the cards on the market''
https://www.pcper.com/reviews/Graphics-Cards/NVIDIA-GeForce-GTX-960-2GB-Review-GM206-199/Overclocking-ASUS-GTX-960-Strix
see that's a cherry picked card sent to them for review not a retail card like you or me buy from newegg ????
you got to take a lot you see on this with a grain of salt from hype sheets / sale pitch reviews .