i took my previously modded bioses and applied the v4.23 rom.by bios patcher to add (later than palomino) athlon xp cpu microcode and fix bus disconnect support. i also selected show actual xp frequencies, but the post screen still reports 2100+ so either it didn't take or the fix refers to another location. i successfully flashed both bioses, but i don't have any later 266fsb cpus to test the new microcode.

here we go again...i've since switched from ps/2 to a usb keyboard and discovered that the default rom.by rollback feature (original bios loaded when '-' keypress or keyboard disconnected) doesn't recognize the usb keyboard legacy support on this board. i re-patched with the /s switch to permanently modify the bios with no rollback option.

I discovered what was causing me issues with my KK266+ Revision 1 and setmul crashing or causing instability -- it was Bios Patcher.

I programmed the vanilla 1101 and setmul works fine at every multiplier except 4 which crashes the system. I am testing with a modded Palomino and not an actual Corvette so I don't know if that's the cause, but I doubt it, and I can live without a 4x multiplier.

So the KK266+ Rev 1 is OK afterall. I think the Rev 2 is just a cost-reduced version like I originally assumed.