How do I check ram latency?

I need to buy new RAM .

• First I need to know speed >> done
• Second I need to know latency >> how ?

All I tried from google.

dmidecode --type memory
dmidecode 2.11
dd if=/dev/zero of=/dev/sda2 bs=1G count=1 oflag=direct 
apt-get install hardinfo
apt-get install sysinfo
cat /proc/meminfo
cat /var/log/dmesg | grep Memory
decode-dimms
update-pciids
lshw -C memory | grep clock
apt-get install lshw
lshw -C memory

What is Latency ?

A delay in transmitting data between a computer's RAM and its processor. Since RAM is not necessarily fast compared to the computer's processor, RAM latency can occur, causing a delay between the time a computer's hardware recognizes the need for a RAM access (initiates a request for data) and the time the data or instruction is available to the processor. If the CPU requests data that is not stored in the cache, then it will have to wait for the RAM to retrieve the data, opening the door to latency problems.

Where to check Latency of RAM ?

For Ubuntu install package i2c-tools and run

sudo modprobe eeprom
decode-dimms

Source : Ubuntu Forums & Major Source

I hope it will help you.

Please use command 1:

sudo dmidecode -t 17 or dmidecode -t memory

output for command 1:

# dmidecode 2.11
SMBIOS 2.6 present.

Handle 0x000E, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x000D
    Error Information Handle: No Error
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 2048 MB
    Form Factor: SODIMM
    Set: 1
    Locator: M1
    Bank Locator: Bank 0
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1334 MHz
    Manufacturer: 830B            
    Serial Number: DBC8287D        
    Asset Tag: 1012
    Part Number: NT2GC64B8HC0NS-CG 
    Rank: Unknown
---------------------------------------
output command 2


# dmidecode 2.11
SMBIOS 2.6 present.

Handle 0x000D, DMI type 16, 15 bytes
Physical Memory Array
    Location: System Board Or Motherboard
    Use: System Memory
    Error Correction Type: None
    Maximum Capacity: 16 GB
    Error Information Handle: Not Provided
    Number Of Devices: 4

Handle 0x000E, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x000D
    Error Information Handle: No Error
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 2048 MB
    Form Factor: SODIMM
    Set: 1
    Locator: M1
    Bank Locator: Bank 0
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1334 MHz
    Manufacturer: 830B            
    Serial Number: DBC8287D        
    Asset Tag: 1012
    Part Number: NT2GC64B8HC0NS-CG 
    Rank: Unknown

Handle 0x000F, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x000D
    Error Information Handle: No Error
    Total Width: 64 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: SODIMM
    Set: 1
    Locator: M2
    Bank Locator: Bank 1
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1334 MHz
    Manufacturer: 0198            
    Serial Number: A30EEB39        
    Asset Tag: 1044
    Part Number: 9905428-012.A00LF 
    Rank: Unknown

Handle 0x0010, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x000D
    Error Information Handle: No Error
    Total Width: Unknown
    Data Width: Unknown
    Size: No Module Installed
    Form Factor: SODIMM
    Set: 1
    Locator: M3
    Bank Locator: Bank 2
    Type: DDR3
    Type Detail: Synchronous
    Speed: Unknown
    Manufacturer:                 
    Serial Number:                 
    Asset Tag:     
    Part Number:                   
    Rank: Unknown

Handle 0x0011, DMI type 17, 28 bytes
Memory Device
    Array Handle: 0x000D
    Error Information Handle: No Error
    Total Width: Unknown
    Data Width: Unknown
    Size: No Module Installed
    Form Factor: SODIMM
    Set: 1
    Locator: M4
    Bank Locator: Bank 3
    Type: DDR3
    Type Detail: Synchronous
    Speed: Unknown
    Manufacturer:                 
    Serial Number:                 
    Asset Tag:     
    Part Number:                   
    Rank: Unknown