That is a pretty high OC for that card unless you are increasing the voltage. Try 900Mhz on the GPU. Just because CCC is stable doesn't mean everything will be. I've had stable OC's that worked for months and then a GPU demanding game comes out and kills it.
i just tried it again overclocked at 930 and 1030, put the fan to 70%, when i checked it out, it was 65°C. It crashed after maybe 3 minutes, the screen turned gray, i could still hear the sound of the game. I had to restart the computer as usually
it works fine, i played at least 15 minutes and it didnt crash. 900 and 1030, should it try 910 or else ?
Leave it at 900 for a while and see where you are at. You can try 910, but OCing is like babysitting a 7 year old with ADHD. You have to keep watching it and even though everything seems fine for a while, it could spaz out anytime. 900 is a nice round number. You can probably get 1050 or more on the memory. I like round numbers to work with, OCD kicks in.
Try OCCT's GPU stress test for an hour, turn on error checking to. 900/1050 seems like a solid OC.