The U.S. Department of Justice has called off a probe into AMD and Nvidia’s alleged price-fixing and marketing practices. The agency had subpoenaed both vendors in late 2006 as part of an anti-trust investigation into the market for graphics processors and graphics cards.

The claims of lack of competition between the two companies were somewhat surprising, since the chipmakers were as fierce competitors with each other as ever. At the time the investigation was launched, AMD had just finished its acquisition of ATI for $5.4 billion, whereas Nvidia launched its GeForce 8800 graphics card. This recent decision allows AMD and Nvidia to keep challenging each other and Intel without the risk of monetary penalties or restrictions to their marketing practices.

A similar private antitrust class action was also started against ATI and Nvidia and settled earlier this year. Both AMD and Nvidia denied the allegations, but stumped up $850,000 each as part of the settlement.