Acer Aspire 3830TG-6494 :: Crashes While Gaming Using Either Integrated Or NVidia Graphics

Acer Aspire 3830TG-6494 crashes while gaming.
 
Crash symptoms:

-happens anywhere from within the first 15 minutes to several hours into a game (no link to graphic quality settings). No loss in performance leading up to the crash.
 
-screen glitches and goes black, with a brief buzzing sound. Power remains on and fan is still running, forcing a hard reset. 
 
-Occasionally the sceen will freeze, ~1cm horizontal green lines will appear all over and a loud buzzing sound is emitted from the speakers until a hard reset. 
 
-Rarely I get a BSOD or the computer will shut down and restart itself. Resulting DMP files show no consistent suspected cause.
 
-Crash will occasionally be preceded by certain in-game sounds cutting out. But not always.
 
-The only link between crashes is that I'm usually thinking a solution worked right before the crash. (Frustrating!)
 
-System will occasionally crash while  watching videos or something, but only crashes consistently while gaming.
  
I have tried the following: 

-Running games using only the integrated graphics or nVidia GeForce GT 540M GPU.
 
-Underclocking either the GPU(500MHz and 700MHz, from 672MHz and 900MHz), the CPU (seting max 70% power plan), and both simultaneously. 
 
-Temperatures do not exceed 70C under heavy use, and crash does not seem to be linked to any temperature increases. 
 
-Run both Windows 7 memory diagnostic and memtest86 (no problems found)
 
-Run intel CPU diagnostics and intel XTU benchmark which did not cause a crash. 
 
-Upgrading all drivers to latest versions, as well as rolling them back to the versions recommended on acer download website. (Completely uninstalling graphics drivers before re-installing different versions) And making sure windows update was not automatically installing driver updates.
 
-upgrading BIOS to v1.12, it was stable for a weekend then went back to crashing.
 
-The system seems to be more stable in power saver or balance mode, but not  by much. I also suspected the Ac power adapter because it didn't seem to crash on battery for a brief time. But I was wrong and it did end up crashing whether plugged in or not. 

Aand cleaning it out w/ compressed air, obviously ... I don't game often, and usually play older games on lower quality settings. I'm not overclocking or streaming at the same time.