its the inverters of the screen, that can be really expensive to fix, unless sending it under warrenty. My 8890 has the same problem and i didn't send it back because i didn't want to be with out my laptop (at the current time). Sometimes i wish i had, but it really hasn't gotten worse for a long time. It started on my laptop over last summer, and most often there is NO flickering whatsoever on my screen.
If i adjust the dim level then i can notice the flickering, so i just leave it at the brightest level and don't touch it. If i were you, i would look into sending it to sager, or finding someone who is capable of fixing/replacing the inverters. Hope you find your solution!