Ideally, one would add matching RAM, and to the extent possible, that’s what I did: I got a 16GB G.Skill DDR-2133 (PC4 17000, 260-pin, CL 15, 1.2V) module on sale at Newegg. Sources suggested that the speed difference between 2133 and 2400 would be virtually unnoticeable, whereas the price difference in this instance was quite noticeable.
Later, when it came time to examine the BIOS information (below), I would see confirmation that the system was recognizing 20480 MB (i.e., 20GB) of RAM. That was because the system arrived with 8GB: 4GB in the Adata stick, and 4GB soldered to the motherboard. I chose that quantity of RAM because I had a habit of multitasking, with a lot of browser tabs open, and experience suggested that my system would be noticeably faster, on many occasions, with more than 16GB. I could have tried a 32GB module, budget permitting, but Acer’s specifications page said 20GB maximum, and I believed them.