When I was doing my Networking course at TAFE, one person tried to upgrade their laptop memory, so that they could run VMs.
One of the instructors helped them choose the memory (after some research).
The laptop wouldn't boot with the new memory.
I'm always "strapped for cash", so I don't want to blow $40.
I could use that cash to buy something else (e.g. put it towards a SSD or another HDD).
I used to work as an electronic repair technician.
It seems strange to me that there isn't a sure-fire way of working out what component to buy.