Nvidia wouldn't just be starting far behind Intel and AMD -- it would be running straight into a "minefield of potential engineering problems," said Brookwood. For most of its 30-year existence, the x86 processor "evolved without a rigorous architectural definition. As a result, engineers creating a newer version had to ensure that it was compatible with all of the weirdnesses and bugs of the older one."

Both Intel and AMD have a strong handle on x86's quirks due to the "historical memory" of the thousands of engineers they employ, as well as the many systems they have for testing and development, said Brookwood.

These were key factors that hurt Cyrix when it unsuccessfully tried to challenge Intel in the mid-1990s, he said.

A reasonably successful maker of low-cost knockoffs to Intel's 386 and 486 chips, Cyrix's problems started when it touted its M1 processor as faster than Intel's Pentium.

Brookwood said that advantage, whether real or not, quickly vanished as early M1s proved buggy. Meanwhile, Intel churned out newer Pentiums that quickly topped Cyrix's chip.