You can check the information by running following command:

 sudo dmidecode --type memory

The result will look like:

vineesh@vineesh:~$ sudo dmidecode --type memory
# dmidecode 2.12
SMBIOS 2.4 present.

Handle 0x0017, DMI type 16, 15 bytes
Physical Memory Array
	Location: System Board Or Motherboard
	Use: System Memory
	Error Correction Type: None
	Maximum Capacity: 8 GB
	Error Information Handle: Not Provided
	Number Of Devices: 4

Handle 0x0018, DMI type 17, 27 bytes
Memory Device
	Array Handle: 0x0017
	Error Information Handle: Not Provided
	Total Width: Unknown
	Data Width: Unknown
	Size: No Module Installed
	Form Factor: DIMM
	Set: None
	Locator: J6H1
	Bank Locator: CHAN A DIMM 0
	Type: DDR2
	Type Detail: None
	Speed: Unknown
	Manufacturer: NO DIMM
	Serial Number: NO DIMM
	Asset Tag: NO DIMM
	Part Number: NO DIMM

Another command also available to check this:

 sudo dmidecode --type 17 | less