Hello, I recently installed new graphics card (GIGABYTE GT 730 Ultra Durable 2 2GB DDR5) to avoid problems with Intel HD 4400 (screen flickering). Although it solved the issue with flickering, new problem has appeared. When using browser or Launchpad (or anything else), screen randomly fades black for a fraction of a second. If it happens within Launchpad, Launchpad immediately closes itself. Overall this behavior is really annoying and disallows me working on this desktop. Here is how it looks: https://www.youtube.com/watch?v=oC7pnWy037w (I hit no keys while recording this video) Occurs in both Mavericks and Yosemite (PB 3), with stock drivers either nVidia web drivers. Can anybody please tell me what is going on here?