graphics card repair

I saw the Graphics Card Necromancy - EVGA 980 Ti Classified and figure this is the right place to ask for inspiration (but as a forum newbie, please (please?) correct me). I was surfing the internet and found an EVGA GTX 980Ti for $50. The seller was up front that it was definitely not working...

I have a Zotac 960 mini and a R9 280X from Asus with a short to ground - the 960 on vMem and the 280X on the upper two vCore phases. Since there is no visible damage on both cards i proceeded to hooking up my power supply and setting it to 0,9V/1,5V. After slowly increasing the current up to 10A...

I have I a PNY 1050 Ti I want to repair - no visible damage or shorts on any voltage rails beside VMem. The resistance to GND is 1.2 ohms - probably a short I thought. Then I hooked my power supply up at 0.9V and slowly increasing the current but the GPU got hot and all memory modules as well...

I have a few GPUs with probably defective BIOS chips. Since they are different and I would like to not have every single eeprom chip in existence in stock in case I need them some time I was curious how far interchangeability goes. Can I just use any SPI eeprom with enough capacity for the bios...

I had a few cards on my hands by now with the same problem - crash on loading windows or login screen. Since I wasn't able to fix any of them I'm curious what can potentially cause this issue. I know about Vram damage, BGA damage, faulty BIOS installation or defective BIOS chip and of course die...

I have started my own small "graphics card repair shop" in which i focus mostly on the generations between Kepler and Maxwell (AMD equivalents in this time periode as well) and would like to know if there are some components which are very comon and prone to breaking and therefor good to keep...