Fastest/best Way To Handle Update

I have a master table which has demographic data such as name, dob, location along with a primary key id. It will have about 10-12000 records. We get a refresh file every hour which may or may not have corrections for these records hourly with about 3,000 records. I put this data into a table. This data should be considered always to be correct. To handle the update to the master table I need to create an update process. I can take one of two approaches, just update all the records in the master table regardless if they are correct or not, or do some type of left join on those that do not match (in other words, only update the ones where thae names or dob don't match) There is an underlying update trigger on the patient master which will also fire if these values are changed. An opinions on a best approach?