Intel stopped at 66 MHz for the DX2. Texas Instruments said "hold my beer" and pushed the architecture to 80 MHz. This rare variant was significantly faster than the standard Intel part, but it required a motherboard capable of running a 40 MHz bus (which was unstable on cheap boards).
It is a beautiful example of the "Clone Wars," where third-party manufacturers like TI, AMD, and Cyrix pushed the x86 architecture harder and faster than Intel was willing to go.
