How to find the frequency and type of my current RAM?

This should do:

sudo lshw -short -C memory

Use the lshw command with the memory class:

$ sudo lshw -C memory
  # Some things about firmware and caches
  *-memory
       description: System Memory
       physical id: 13
       slot: System board or motherboard
       size: 8GiB
     *-bank:0
          description: DIMM [empty]
          product: [Empty]
          vendor: [Empty]
          physical id: 0
          serial: [Empty]
          slot: ChannelA-DIMM0
     *-bank:1
          description: SODIMM DDR3 Synchronous 1600 MHz (0.6 ns)
          product: M471B5273DH0-CK0
          vendor: Samsung
          physical id: 1
          serial: 34A8C7AF
          slot: ChannelA-DIMM1
          size: 4GiB
          width: 64 bits
          clock: 1600MHz (0.6ns)
     # More banks.

As you can see, I'm using DDR3 1600MHz RAM.

Another option is dmidecode:

$ sudo dmidecode -t memory
# dmidecode 2.9
SMBIOS 2.5 present.

Handle 0x003B, DMI type 16, 15 bytes
Physical Memory Array
    Location: System Board Or Motherboard
    Use: System Memory
    Error Correction Type: Multi-bit ECC
    Maximum Capacity: Unknown
    Error Information Handle: Not Provided
    Number Of Devices: 8

Handle 0x003D, DMI type 17, 27 bytes
Memory Device
    Array Handle: 0x003B
    Error Information Handle: Not Provided
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: DIMM
    Set: None
    Locator: DIMM_A1
    Bank Locator: NODE 0 CHANNEL 0 DIMM 0
    Type: Other
    Type Detail: Synchronous
    Speed: 1067 MHz (0.9 ns)
    Manufacturer: 0x0198
    Serial Number: 0xB12A9593
    Asset Tag: Unknown
    Part Number: 9965426-037.A00LF 
# more such devices

This is for a server with ECC memory (as can be seen from the Error Correction Type field and the difference between Data Width and Total Width).

Both tools are dependencies of the ubuntu-standard package and should be available by default on all Ubuntu systems. There used to be another tool called hwinfo, which is no longer available for Ubuntu since 13.10.

I could only get this info with dmidecode, but rather than grepping, it's cleaner to use the right type:

sudo dmidecode --type memory