I bought an alienware M15x back in 2011, and after a year or so I replaced the Geforce 260M with the more powerful 460M and bought a couple more gigs of ram. I've also had to replace the power supply as it was no longer charging my battery (this fixed the problem)

A little less than a year ago this thing started doing weird stuff on occasion, namely blacking out the screen and flickering for a couple of seconds before returning me to whatever I was doing.
Some programs would incur this wrath more than others, so at first I just worked around it.

But eventually I got sick of it when my favourite games started doing it frequently. So I reformatted my computer completely, figuring it was some software thing from files now 3 years old. But it did absolutely nothing.

Now just in the past couple of days I've been getting a really bizarre symptom:
As soon as I start ANY game, even just let it open into the menu screen and do nothing, my GPU temperature will immediately skyrocket 10-15 degrees, then steadily climb to over 90 degrees celsius in 5 or 10 minutes!

I figured it must be something wrong with airflow so I cleaned the hell out of my all my components, my fans and heat sinks, and re-applied thermal paste where needed... but to no avail.

If I hit stealth mode, the temperature will very quickly drop back down to my regular 50 or so idling GPU temperature (except then I can't play any good games obviously). As soon as I turn stealth mode back off, if I have a game running even in the background at the start menu screen, the temperature will skyrocket again.

I've run countless diagnostics, updated my drivers, taken my laptop apart again and made sure all components were properly in place, and I acquired means to manually ensure my fan speed was up to par (it was fine).

Keep in mind that just a few days ago everything was working well with the exception of the occasional screen flicker

Is this my Video card that just needs to be straight up replaced?? I don;t want to do this if I don't have to but my options are looking slim...

Here are my Specs: (I have not overclocked anything)
Intel i7-740QM
Nvidia GeForce GTX 460M
6GB Ram (DDR3 I believe)
Intel PM 55 Motherboard

Running Windows 7 Home Premium (x64)

Currently have BIOS vers. A09
At least 300GB of free space on my regular (no SSD) Harddrive

All drivers are up to date.

Any suggestions would be appreciated as long as it's not "It's your airflow!" or "Update your video Drivers!" or other stuff that I obviously tried immediately.

Cheers.