But the specs of the processor tells that <memory type ddr3 1333/1600>what does it mean?
Short answer, nothing.
Long answer, that is all Intel has bothered to validate with and doesn't have the time or money to validate every RAM manufacturers speed, XMP settings, etc. etc.
A bigger concern is finding a RAM kit that is on your MOBO's QVL (Qualified Vendor List). Every board manufacturer has a list of the validated kits that they know will work in the board, and even then it's fairly similar to Intel's 1333/1600 policy where other kits will work just fine in the board, however there is no guarantee.