Check Ram Speed and Type on Linux

How to check the memory speed without opening the computer case? An easy way to do that is using biosdecode command line utility. Dmidecode is a tool or dumping a computer’s DMI (some say SMBIOS) table contents in a human-readable format. The output contains a description of the system’s hardware components, as well as other useful pieces of information such as serial numbers and BIOS revision. This command works under Linux, UNIX and BSD computers.
Type the following command in a shell with super user privilege

dmidecode --type 17

will give you the memory infomation like this

SMBIOS 2.5 present.

Handle 0x1100, DMI type 17, 27 bytes.
Memory Device
        Array Handle: 0x1000
        Error Information Handle: No Error
        Total Width: 72 bits
        Data Width: 64 bits
        Size: 4096 MB
        Form Factor: <OUT OF SPEC>
        Set: None
        Locator: DIMM 1       
        Bank Locator: Not Specified
        Type: <OUT OF SPEC>
        Type Detail: Synchronous
        Speed: 667 MHz (1.5 ns)
        Manufacturer: 80AD808980AD
        Serial Number: 4266120A
        Asset Tag: 010810
        Part Number: HYMP151F72CP4N3-Y5

Handle 0x1101, DMI type 17, 27 bytes.
Memory Device
        Array Handle: 0x1000
        Error Information Handle: No Error
        Total Width: 72 bits
        Data Width: 64 bits
        Size: 4096 MB
        Form Factor: <OUT OF SPEC>
        Set: None
        Locator: DIMM 2       
        Bank Locator: Not Specified
        Type: <OUT OF SPEC>
        Type Detail: Synchronous
        Speed: 667 MHz (1.5 ns)
        Manufacturer: 80AD808980AD
        Serial Number: 42661005
        Asset Tag: 010810
        Part Number: HYMP151F72CP4N3-Y5