Alienware M18x R1 - automatic restarting issue & no service tag available

Dear users,

I recently got this laptop and had been working perfectly well until a few days ago, when it started giving me screen glitches and random restarts. I performed the ePSA diagnostics and there were no failures shown. I presumed it to be an issue with the video card, but then my laptop should have never started and should have given me 8 beeps error code all the time. Though, i once got the 8 beeps but upon restarting, it went away. Also, the laptop restarts right after the windows logo is flashed on the screen.

I would appreciate if any of you can help me. The most weird thing to discover was that the laptop actually havent got a service tag label on the panel, neither there is one in the CMOS.

Thanks.