Alienware M17x R3 Disabling PSU

Hello and thanks for taking a peek. I am at a diagnostic dead end, I cannot figure out if my Motherboard on my Alienware M17x r3 is failing or my gpu, a 7970m failed.
Randomly while gaming my computer shut off, no BSOD nothing just kaput....
I tried restarting by pressing the power button nothing, noticed that the ac adaptor cable light connected to the back of the laptop was not turning on. So I unplugged the ac adaptor and plugged it back in, the blue light came on. But when I plugged it back into the laptop it immediately shut off. At this point Computer wont turn on at all, nothing no beepds or sounds or fans turning on.
So I opened her up to check for anything lose or anything that could be causing some type of short, nothing. So I removed the gpu, and it started up. I then re installed my faulty 6990m and again it starts up flawelesly, except with the artifacts and black screens caused by my failed 6990m. At the moment my machine is running with the 6990m installed and disabled so it is usable.

My question is, could a GPU cause some type of short to cause the laptop to disable the ac adaptor and shut itself off completely or is the motherboard failing? (Also my 7970m is about 10 months old was bought brand new)

Again thanks for taking a peek, and hope someone can shed some light so I can replace the failing part on this laptop.

 

Either the brick went and then the battery drained or yes short on the board. Get another power brick or test yours in another system.

 

Thanks for the reply! I am leaning towards a failing motherboard, since without the 7970m installed the Laptop works fine and continues to charge the battery.