President Joe Biden has proposed new limits on AI chips made by manufacturers including Nvidia.Justin Sullivan/Getty ImagesPresident Joe Biden has proposed new AI-chip export curbs to limit access for China and Russia.The restrictions aim to concentrate advanced AI development in US-allied countries.About 15% of Nvidia's revenue last quarter came from China and Hong Kong.President Joe Biden has proposed one more round of export restrictions on AI chips, set to affect those made by Nvidia and AMD, with the goal of limiting China's and Russia's access to chips for training artificial-intelligence models and powering data centers.A White House announcement on Monday said chip sales to 18 US allies would be free of restrictions and controls would not apply to chip orders below certain computation thresholds.The proposed rules, which also aim to help businesses around the world align with American standards, are set to take effect 120 days from publication.Under the restrictions, entities outside close US allies would still be able to purchase up to the equivalent of 50,000 advanced graphics processing units per country.In a blog post published Monday, Nvidia criticized the plan.