I have the Acer Nitro 5 AN515-31 and it has 8GBs of RAM at a frequency of 2400Mhz. According to the Task Manager, 2 of 2 slots are filled. But there is only one physical RAM slot when opened. So I presume that one is soldered. I want to upgrade the RAM. Can I use 8GB of RAM in one slot to make it 12GB of RAM? Also, what would happen if I were to use 16GB+4GB RAM sticks?! Please help.