I was already considering buying the SSD and RAM myself, so that's good to know.

This sounds like a similar issue I've had with my own computer. I assumed the problem was that the board is form 4th gen intel, DDR3 RAM, and it definitely doesn't support an EVO 970 since it's from ~2014. I had to put the bootloader on another drive to avoid this. Not a very pretty solution, but it still works!