Need help overclocking my msi7970 oc edition..

Hey guys this is my first time overclocking and i cant seem to get it right at all. i just purchased this card yesterday so its my first high end card... aside from the 1 gig 6950 i upgraded from. Well i am extremely happy that i can play bf3 maxed out finally. i usually average at about 75-80 fps. well as i said this is my first time oc'ing. i keep trying to oc the card further and after about 10 to 15 minutes of gameplay the card crashes. i remember reading somewhere that the 7970 should be able to reach the lvl of the 7970 ghz edition easily... which i believe the core clock is atleast 1100. now mines is 1010. well heres a link of my card...

http://www.microcenter.com/product/403016/R7970-2PMD3GD...

i know i dont really need to oc as of yeet but its something i really wanna know. ive been to many different forums and cant seem to find a solution so im hoping you guys can assist me with this problem. i also know my card isnt bottlenecked in any way because im good in all other areas but this one. i also have tried lowering things once it crashes and still nothing even with the slightest oc it crashes. the one other thing that i dont understand is what the power limit option is about and what should i have it at? at first i thought this was an overheating issue but i tested having the fan speed on 70 and still same problem.