240W Flextronics Adapter
Most likely, that is your issue. My 15 R3 shipped with one, and DELL swapped it out by sending me a whole new one when the AC Adapter would turn itself OFF while being plugged into my laptop, and the wall.
No issues with a DELL manufactured one. Got told there were some adapters shipped with units that weren't properly manufactured. Recommend buying a new one if your warranty is up, which it most likely is.
Might I recommend before you buy however, google DDU (Display Driver Uninstaller) and running that, then reinstalling current driver to see if it fixes your issue before you blow roughly $70 on a new one?