Nvidia has filed a patent-infringement suit against 3dfx, which has vowed to fight the action.

The lawsuit covers five patents that Nvidia claims 3dfx has infringed. It is applying for an injunction against 3dfx restraining the company from manufacturing, selling or importing the offending graphics chips and cards. It is also seeking monetary damages.

Nvidia's move follows an earlier patent-infringement suit filed by 3dfx against Nvidia in September 1998.

The 3dfx products at the centre of the Nvidia action are the Voodoo3, Voodoo4 and Voodoo5 chips, as well as the VSA-100 family of products.

3dfx announced last week that its VSA-100, or Voodoo chip has been adopted by the US military as the technology to drive its training simulations.

3dfx has vowed to fight the suit, with Alex Leupp, president and CEO of 3dfx, saying: "Nvidia’s suit is clearly an attempt to force a settlement of our existing patent-infringement suit against the company, and we believe it shows a lack of confidence in their defence.

"We anticipate receiving rulings as to ‘claim interpretation issues’ in our existing lawsuit shortly, and we are committed to protecting our intellectual property."

Leupp added: "We regret that Nvidia feels compelled to resort to these kind of tactics in defence of the pending litigation. 3dfx will vigorously defend itself against this litigation."