Yaaaay I figured out what was wrong with the secondhand Yoga I bought!

For some reason one of the DIMM spaces was really sensitive to case pressure. I started suspecting as much when I had two sticks in and the VRAM got scrambled in a *checkerboard* shape.

I switched out the two 8GB sticks that came with it with the single 16GB that was in the other spare thinkpad, and it works without any disruptions whatsoever!

I have a drawing tablet computer again! \o/