Flashing screen, faulty video display cable?

Hello

Recently my MBP (2.5 years old) screen started flashing (from 4 times/min till maybe 10 times when it warms up). In the apple service they replaced all the logic board, because according to them: nvidia gt 8600 was broken. However it doesn't helped and my screen keeps flashing. Apple technician says that the screen works perfectly fine, except that it flashes.. However he suggest me to replace the screen and it costs a lot...

I wander if it can be not the screen problem, but video display cable fault??

P.s. there're no flashes seen on the external monitor, when it's connected to my mbp.