Originally Posted by ritesa

In Germany, an "identification card (BahnCard, bahn.bonus Card, credit cards*, ec-card/Maestro or ID card**) for booking over the Internet and as identification during fare controls on the train" is required - the ID you entered while booking the ticket needs to be the same you have with you on the train.

* American Express, MasterCard, Diners Club, Visa or JCB

** The ID cards of the following countries can be used as identification on the train: Germany, Austria, Switzerland, France, the Netherlands, Belgium, Luxembourg, Italy and the Czech Republic.

(http://www.bahn.de/i/view/DEU/en/pri...neticket.shtml)

Don't know about Czech Republic and Austria, but as you have a passport with the correct name it should not be a problem. If you're asked about this, just explain it.