I can't give you concrete answers to the video problem, but I do know that the Vbios of the video card is matched to the particular configuration of the system BIOS's of the laptop model they are put in. I believe this has to do with the ME monitoring temperatures and running fan speeds, The BIOS for which display to put video to by default and what the correct display modes are, as well as coordinating the Backlight power with the GPU and power delivery. That's mostly my speculation based on behaviors I've seen in the past.
As far as the memory goes, I believe that model has four slots for RAM, two on the bottom, two under the keyboard. Try different slots to see if some work better than others, and run Memtest86+ on each stick individually to see if one of the sticks of ram is less optimal than the other. Sometimes the sticks of ram test good, but don't play well with each other, and one, or both need replaced. Sometimes that model takes a good two minutes before it finally resolves an acceptable RAM timing solution, reboots and posts normally, so be patient with it. (this is usually only when there are issues with ram sticks agreeing with each other.)