It may just be a GPU hardware problem.  I would advise checking what you have open when it occurs as it may be the cause.  Not very helpful, but you never know.  Also use CMD to scan your hardware.

I have the same problem and I have the exact same graphics card, a Geforce 675m. This is a common issue from what I've seen on the internet and I've spent countless hours trying to fix it myself by uninstalling the drivers, reinstalling other versions/going back to certified drivers, deleting all the nivida folders from my computer, changing TDR settings, display driver uninstaller, resetting the bios settings, everything. We really need to get some assistance on this from Dell and/or Nvidia. It looks like almost everyone with the 675m has this problem after updating their drivers. I take amazing care of my things and I have NEVER had one problem with this laptop until I installed one of Nvidias last graphics driver updates and now I get a black screen after a few minutes every time I play a game or watch a video. It is NOT a hardware problem because my graphics card, mother board, etc. all pass every hardware test every single time and sounds like that's the case for you as well. Don't listen to the guy below, this problem is far too widespread to just be a hardware gpu problem., so many people are having with the 675m are in an identical situation and so far there hasn't been any solution. I love my laptop and I just want to get it working again. Hopefully a representative will see this thread and help.

I have the EXACT same problem and done all the same steps! Done rollbacks on drivers and uploaded the latest to no avail. Please PLEASE can someone at Dell/Alienware and Nvidia at the VERY least look into this? Would really like to use my laptop again.