The U.S. Patent and Trademark Office upheld Rambus 's patent-infringement case against Nvidia Corp.Rambus and Nvidia have been battling over patents since November 2008.

A ruling is still being awaited on the complaint Rambus made back then to the U.S. International Trade Commission, saying Nvidia memory controllers that it said infringed nine of its patents.

In an initial determination in January, a judge ruled that Nvidia infringed on three of those Rambus patents.