Name check is same as back ground check. This happens towards the end of the whole approval process.
Raj_nsc, u are talking about fingerprints, they are different than the name check process. FBI Fingerprint checks usually happen in just a day, but name checks is a much more rigirous and extensive process and it can take up to a year for your name-check to be complete. Especially if you have a common name, are from a special registration country, have any records or something like that.
Lot of time, the IIO takes an interview, but does not stamp the passport, because he/she has to still hear from FBI to return the name check result.