After reviewing the Lenovo ThinkPad P50, I decided to double the RAM from 16GB to 32GB. You can buy it with more RAM, or install it aftermarket. The RAM that came with mine was Samsung brand, but I bought and added Kingston DDR4 RAM with no issue.
Depending on your RAM configuration, you may just need to add RAM to the bottom of the laptop – as mine already had the sticks under the keyboard.
Lenovo have some great guides on how to take the laptop apart, which I followed:
Step 1 – Remove Battery
Step 2 – Remove Bottom Cover
Step 3 – Take Keyboard Off
Here’s a video I created on opening up the laptop and adding the RAM based on this:
Any questions please ask below!