Display problem on Alienware M17x r4

Hi there! I have this really weird bug, I dont know exactly what is the problem. I'm out of warranty and I seriously want to spend the less money I could on this: this is my 3rd dell laptop since 2009 and they all had some hardware problem (first one was inspiron 1720 bought in 2009; still running good and it's the reason why I bought two more... I had to change the screen within 2 years, but other than this, it's running good; got a XPS L701x and mobo died within 1 year and a half; then, I decided to buy an alienware, expecting to keep it for like 5 years like my inspiron... but got some weird hardware problem within 3 years...). Anyhow... ranting over... :P

So here is the details for my problem:

I have an Alienware m17x r4.
Dedicated Graphic card is NVIDIA GeForce GTX 660M. Integrated graphic card is an Intel HD Graphic 4000.

The screen is all fuzzy, with tiny blurried line. This happen not only in windows, but also when booting the computer (I see those line as soon as I power on the computer)
Like this:
http://i.imgur.com/srV3IH6.jpg

Here is a closeup:
http://i.imgur.com/iGlYsl1.jpg

I though my screen was the problem... but if I do plug a HDMI cable from the HDMI out to the HDMI in and press Fn-F8 (HDMI In), I have a perfectly working screen.
http://i.imgur.com/50Dqlpf.jpg

Obviously, I dont have any problem using an external monitor.

Some strange behavior:
- While using HDMI, my resolution is 1920x1080 (but I can't go higher than 1600x900 if I dont use HDMI in/out trick). 

Troubleshot tried so far:
- Updated all drivers.
- I disabled the Nvdia driver.
- I disabled the Intel HD 4000 driver.
- I disabled the Intel HD 4000 by pressing Fn-F7 and reboot the computer.
- I did physically remove my dedicated videocard.
- I tried booting with each one of the memory stick, separately.
- Downgraded my bios from A13 to A12 as A13 seems to be not supported (?).
- Reset my bios by unplugging the battery and CMOS battery and hold power for 30 seconds.
- I did open the laptop and inspect every connection.
- I ran a full diagnostic from Dell. (didnt find any problem)
- I ran a full diagnostic from Bios. (didnt find any problem)

Extra info:
While connected via HDMI, I can disable my GTX660m from device manager. GPU-z software shows no activities from that card (660m) and screen is perfectly working. So now, I think the problem is the GTX660m may be faulty. 

Weirdly enough, the problem was still there when I physically unplug GTX660m from laptop. Maybe I have something else to do in Bios / windows as well?

Any idea, anyone? I dont really care to ditch the GTX660m and run exclusively on integrated graphic card... as long as I dont have an HDMI cable running from one end to the other on my laptop! :P

Any idea, anyone?