M17X r3 - Black screen after windows boot

Hello,

I've had my m17x r3 since 2011 and have never really had any problems with it.
Now a week ago I pushed the start button, waited for windows to load and to my surprise the screen turned black.
I've researched and researched but have yet to find someone with the same issue.
I'll quickly summarize the issue I'm experiencing;
After waiting for windows to load (which now takes noticeablyt longer than before) the screen turns black and there is no back lighting.

Things I've tried:

• Reformat
• Tried various old and new drivers for the GPU
• Booted in safety mode (works)
• Made it boot using the integrated intel HD GPU (works)
• Booted without the ATI GPU drivers installed (works)

I thought the GPU was fried but when I look in the boot menu, device manager or even the driver package it's simply there, so it is noticed and functioning (at least I think so?).
I've also done the screen test at boot and it works flawlessly (where you hold D, I think, and the colors start popping up).
2 Days ago I opened it up and looked at the GPU but it still looks fine as far as I can see, no noticeable damage or anything.

Oh and 2 months ago or so, the laptop started having a black screen when it came out of sleep-mode.
The day before I tried booting it it worked perfectly however and it didn't display any weird behavior or anything, I simply shut it down the evening before.

The thing is, my m17x is out of warranty and Dell's support is quite limited for OoW customers to say the least..
Any ideas on how to resolve this? Or how I can get it fixed, if anything is malfunctioning?

EDIT: Oh right, the GPU is a ATI 6990m.

 

have you tried hooking up and external monitor, and im assuming it boots to bios and shows the bios screen, the lcd controller board on the back of the lcd may have gone bad if you dont get a picture after it switches to a high res, that's usually a defect it the orig product, could be a broken driver of some sort also, have you tried uninstalling the drivers in safe mode (tick the box that says to delete the driver) and rebooting to let windows install it's default drivers, cause that can also be the culprit, it could also be that when your video card switches modes it senses a fault somewhere and shuts off, had a desktop with a bad video card, worked at bios, worked in safe mode, but anytime the display went over 1024 x768 i would lost picture completely.