AMD said Thursday that the company has signed up 40 developer studios tha plan to use its Mantle technology, and is issuing new invitations for others to access a new portal. The Mantle NDA Developer SDK website is open to professional game developers that are interested in evaluating and developing games with the Mantle API. AMD says that only a limited set of developers will be provided access to the Mantle NDA Developer SDK and access is subject to a selection process.

AMD did not say who has signed up for the program so far.

"There are no objective criteria for being selected, as we are interested in talking to developers of all shapes and sizes," the company said in a statement. "Past development experience is encouraged, however." The password-protected developer portal is now live, AMD said.

AMD launched Mantle in September of last year as a low-level programming interface. Mantle was written by AMD specifically to accelerate games and other apps written for its chips and its Graphics Core Next architecture.

AMD hopes that attracting developers will create a critical mass of game titles which will, in turn, entice gamers to buy only AMD parts when either upgrading or outfitting new PCs.