i dont speak eng very good, so i try to explain my self
i do OC to my HD5770 Vapor-x: GPU CLOCK-960
i do a test for 30 min in OCCT, the test was very good
i play bioshock 2 and after 3 hours the screen start to filcker and i have a black line for 1 sec
i try a test again on occt, after 3 min i have a screen filcker and black lines
so i try to down on the mem clock and gpu
i do GPU CLOCK- 945
and again the test pass but after i play games for 2-3 hours i have artifacts and again i do test but dont pass
I checked the temperatures after the tests it was 63c
the fan on 60%
i try the new driver-10.2
plz help me i dont know what the problem , this is a Artifacts or is Somthing else
if i do mem clock 1370 agian is filcker Instead but in the first time it was ok
Might want to try lowering the core clock OC - with DDR5 the RAM has error correction so as the OC starts to give errors they are resent slowing down the card unlike DDR3 which would wind up with artifacting - so even though the card seems stable at that OC it is possible that it is too high and is causing problems due to an excess of errors that are needing to be resent slowing further processing.
Even if your card isn't running extremely hot you can still have artifacts. This is probally because you're pushing your card to/above it's limits. As JDFan said just lower the OC a bit, and if it's still giving artifacts lower it again till the artifacts are gone.