Nvidia today announced that the U.S. Patent and Trademark Office (USPTO) has initially rejected an additional eight claims challenged by NVIDIA in two patents that Rambus has asserted against it in litigation.

This follows the USPTO?s rejection last month of 41 other claims in seven patents that Rambus had asserted against NVIDIA.

"We are pleased that the USPTO decided to review the patentability of these two additional Rambus patents and continued to agree with NVIDIA's challenge to these eight claims," said David Shannon, NVIDIA executive vice president and general counsel. "The USPTO has now initially rejected all of the patent claims asserted by Rambus against NVIDIA in the ITC."

The ITC litigation involves memory controllers related to graphics processors. Rambus wants Nvidia to pay royalties on these memory controllers used in Nvidia graphics chips.

The dispute began in June, 2008, when Rambus filed suit in federal court in San Francisco charging that Nvidia had infringed 17 patents.

Nvidia is also involved in a dispute with Intel over a licensing agreement. That is being played out in a Delaware state court.