Serious hardware problem

[Jeno]

Running on my high-power GPU makes my laptop turn off (not shut down, not BSOD, no thermal shutdown, just ploop, off).
I can't run any proper games on the intel chip obviously, so unless it's not a hardware failure and I figure something out ( chances of that are almost 0 by now) then there might be no way but to send it off to HP. That would be really bad, as I really need this laptop for not only gaming, but also school very soon for my retake exams.

So, to solve the problem, I have formatted hard drive and reinstalled windows (166 windows updates still need to be applied at time of writing) and all drivers.
Interesting to note is that I can't get image on the laptop screen whilst running on the AMD chip, but can get image on external screen. Didn't have that problem before I reinstalled. Normally I could fix it by switching back and back again between graphics processors, but now it's staying. Graphics drivers have always been a big problem but the problem existed before I reinstalled, so yeah.

It cannot be a software issue as a clean windows still had the issue. It even crashed in the friging POST screens...
I've ruled out RAM, HDD and battery faults by doing respective checks.
It's also not an overheating issue, the heat is fine, i never saw it go above 70, it used to get to 90-95 then shut down to prevent damage. (that's a long time ago though, since then HP has replaced the entire cooling system).

I'm thinking it has to be the dedicated AMD gpu, as I've been running on the intel chip for a long while now with no crash. Not sure what / if anything I can do about it, though. Can try older drivers again, I suppose, but I've had the current drivers for well over a month before the problem first appeared, two days ago. Also, I haven't moved it around in weeks, I have taken it to school every day for the past three years. (it's close to 3 years old, one month warranty left...)

Any input is seriously appreciated.

Note: I have a HP Envy 17 -2130eb notebook with an AMD 6850M gpu, intel i7-2630QM cpu and 8gb RAM.