Here are some commands for query ram related information.
Q1. How many slots?
A1. sudo dmidecode | grep -P -A5 "Memory\s+Device" | grep Size | grep -v Range
Q2. The maximum capacity supported.
A2. sudo dmidecode | grep -P "Maximum\s+Capacity"
Q3. RAM frequency.
A3. sudo dmidecode | grep -A16 "Memory Device" | grep "Speed"
References:
http://linux.chinaitlab.com/command/837383.html
