the classic has a 50MHz cpu and the ipx has a 40MHz one.

> I've used both the IPX and the Classic.  The biggest difference between
> them I've found is that the IPX has a cg6 and the Classic has a cg3.
> (The cg6 has tons more hardware smarts.)  The Classic is faster in some
> respect; the Classic onboard cg3 is visibly faster than an IPX with
> SBus cg3, but I don't know whether that's CPU speed or I/O bandwidth or
> a better interface to framebuffer RAM or what.  The general feel is
> close enough that I doubt it's just raw CPU speed.