Hi, i have an Asus N55SL and i'm having the same issue for a month which is driving me insane. i surfed a lot of forums, websites and everything related to this issue. i just discovered it is not the RAM or Hard Drive malfunction. It is just about the NVIDIA drivers. since they release new drivers for new GPUs and new games they somehow neglect the old GPU holders. NVIDIA is giving a very bad service these days. so i just give you some advise which may help you deal with it. (not worked for me, worked for some people) - first of all if you are able to reinstall your windows, just do it. otherwise skip it (which is not recommended) - remove your NVIDIA Driver with a proper driver uninstaller like this one: Display Driver Uninstaller - Try to roll back to 314.22 by performing a clean installation. you can download it from NVIDIA website. - after installing and restarting your notebook, do this one: NVIDIA Control Panel>adjust image settings with preview>use my preference emphasizing: Performance well, for me...