A.I. companies are buying up memory chips, causing the prices of those components — which are also used in laptops and smartphones — to soar.

The agreement with the start-up Cerebras is the latest in a series intended to expand the A.I. company’s computing power.

Nvidia’s position as the dominant supplier of AI chips may be under threat from a specialised chip pioneered by Google, with reports suggesting companies like Meta and Anthropic are looking to spend ...