The proAptiv's smaller die size will help cut silicon costs for manufacturers and lessen power consumption, Throndson said. And MIPS expects to charge manufacturers a lower license fees than ARM, he said.

It takes more than good technology to challenge ARM's dominance in mobile devices, however, said Chris Rowen, founder and CTO of Tensilica, which designs and licenses dataplane processor cores and who saw the MIPS presentation at Hot Chips Tuesday.

ARM has numerous factors on its side, he noted, including a big ecosystem of customers and partners, and software developers who are familiar with its architecture and its tools.

"Building a high quality architecture -- and there's every reason to think proAptiv fits that category -- gives them a shot," Rowen said. "But it's also the case they have to play the game around ARM's rules, and that's tough."