Toshiba Laptop BSOD vídeo_tdr_failure troubleshooting

[zebrajr]

Hello,

First off, let me start by apologising by any spelling error or lack of formating on the thread but I'm currently writing this thread via my android phone.

Having that said, down to the subject:
I have a Toshiba Satellite L505-13E for the past 4/5 years.
Yesterday I was using the computer as usual, did a Skype call down the road and before hitting the bed I went to watch a movie (with VLC if that is of some importance). 30 seconds after the video started to play I started to get a glitching visual errors (random lines, varied colours, all around the screen, square shaped) not filling the entire screen but still very noticeable.
Within, maybe 15 seconds, my Windows (8.1) gave a BSOD about vídeo_tdr_failure.
(yesterday, 4-5 hours before I did got a "graphic card stopped responding, failed to restart" notification but after manually restarting my laptop everything went back to the usual (no BSOD on that, just a freeze and a manual restart)
Since it was kinda late I've left the laptop unplugged and today morning I've disassembled the laptop (done that before, every 3-4 months for the past 2 years to clean the cooling fan and the internal boards) but everything seems to be in the right place, no broken or loose parts or anything like that. After reassembling my laptop I've noticed that the issue still prevails, both in Windows 8.1 as in Linux (tested with 2 different distributions) and also on boot and BIOS configuration.
I've run memorytest86+ through GRUB manager which passes without any error or failure.

So after all this I would like some help on how to be sure if the problem is from the graphic card and if there is any possible solution or testing that I can still run to see if I can it get working again or if it's time to buy a new one (or some other solution anyone can recommend)

If necessary I can attach a photo of the glitches on the screen.
Any other info or tests feel free to ask them and I will answer them ASAP.

Thank you in advance for the time spent on this issue,
zebrajr

 

[popatim]

Since you've taken it apart to clean the coolers, Have you ever bothered to replace the thermal paste?

 

[zebrajr]

@popatim Yes I did. It never Overheated to the point of freezing or shutting down in these years I've used it (in case you wondering, yes I brought it brand new from a store).
I've checked with CPUz and it never reached critical or maximum temperatures (even doing times of intensive CPU or GPU usage). I also have the computer to shutdown at temperatures below the maximum recommended (which sometimes slowed the CPU usage for a bit till it cooled off a little more) so I doubt this happened because of overheating.

I still think is the graphic part of the Motherboard that is giving the last breaths (since I can turn on the computer, go to the BIOS, SO, etc) but if it cannot be fixed I need to consider options to get a new one and get this one to some kind of use, or in last case, sell it for pieces.

Sincerely,
zebrajr