According to Nvidia on Tuesday, the U.S. Patent and Trademark Office has initially rejected an additional eight Rambus claims that Nvidia challenged.
The additional eight claims are based on two patents that Rambus has asserted against Nvidia in litigation. This follows the USPTO's rejection last month of 41 other claims in seven patents that Rambus had asserted, Nvidia said.
Rambus filed patent claims against Nvidia in an International Trade Commission action in November. The ITC litigation involves memory controllers--which handle communications between memory chips and other silicon--related to graphics processors.
"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, in a statement.
Rambus, which develops high-speed memory chip technology, also commented on the announcement.
"As part of the multi-pronged approach to delay paying Rambus for our patented inventions, our litigation opponents have filed requests with the U.S. Patent and Trademark Office to bring into question the validity of some of our patents. We have seen this tactic for years," according to a Rambus statement Tuesday. "This is a very long process, and the patents remain valid during the whole process," Rambus said.
Rambus is seeking to block importation and sale of Nvidia products that it claims infringe on its patents.
The ITC case goes to trial in August and a final determination is expected in 2010.