Random black screen + lockup (GW2, Skyrim)

Effects: Black screen (loss of vid signal), controls locked out. My only option is to hard reset.
Context: This occurs mostly while playing games (Guild Wars 2, Skyrim) but also while streaming shows and more rarely while being idle (not sleep mode). Never occurs while simply browsing or using youtube, social networks, etc.
Frequency: Inconsistent. It may occur 3 mins in a game, or an hour. Started around december 5th 2013.

Processor: Intel(R) Core(TM) i7 CPU 860@2.80GHz
Hard Drive: Western Digital CWD1001FALS-00YG6A0 ATA device (1TB)
Video card: Asus HD7870 Series
RAM: 16GB (DDR 3)
Motherboard: Intel DH55TC
Monitor: Samsung SyncMaster 2494HM (included just in case).

Steps already taken:
- Driver updates (all)
- Windows updater (important and optional updates)
- Dusting
- Changed my video card from HD 5800 to the current one. Problem was not solved.
- Reinstalled a fresh copy of Windows 7. No change.
- Considering sacrificing sheep to elder gods...

I am now at a loss for the next steps to be taken. I apologize if this is not the right thread as my computer does not crash per say, although the hard reset seems to be my only option anyways.

Thank you.

It would seem that Windows updater lies. I manually looked up every manufacturer site and downloaded new drivers. System is now stable.