Hi, First of all here is my configuration: Processor: 3,5 GHz Intel Core i7 Graphic card: NVIDIA GeForce GTX 780M 16 Go 1600 MHz DDR3 System: OS X 10.9.1 The problem: the screen randomly flashes to black for a second. It occurred for no particular reason. Here is a video of the problem: https://vimeo.com/87096982 What I've done so far: -Resetting the VRAM and PRAM -Resetting the SMC -Turn it off, unplug it and plug it back in. Why I don't think it's the graphic card: When I plugged my imac to my tv using the thunderbolt port it works fine on the tv screen but it still flashes to black on my imac. Any suggestions ? Thanks in advance.