Can I use 16GB of RAM in a 2012 MacBook Pro?

Regarding the MacBook Pro: Yes, you can use two 8GB sticks for 16GB total. Apple officially says 8GB max, but that’s a conservative spec — the hardware handles 16GB just fine. Use a matched pair of DDR3 SO-DIMMs at 1600MHz (PC3-12800) from Samsung or Crucial. If you get boot loops, reset the NVRAM/PRAM and reseat the sticks.