Hmmm wonder what it's like with an 800 Mhz FSB P4 when you do L1 off, Pentium class? then maybe L1 off at 533 is 486 and at 400 is nearer 386 (bearing in mind multi lower on 800 chip, so at 400 it's at early willamette clock speeds, but IPC might be higher)
Though I guess I could scare up the P4M 1.8 I thought I had kicking round somewhere, and see how speedstep behaves.
Edit: reviewing my options of hardware to play around with this on, and I don't seem to have a "goldilocks" CPU or motherboard combo, stuff that's either too good or too bad. Too good mainly meaning I've got different plans for it already. In investigating whether a 331 Celerunt would take 200/800Mhz I found that there's an additional FSB step that might be available on some socket 775 boards. Intel specced a 166/667 FSB which they never released a desktop CPU for, but only used on mobile. However, it might have been implemented with correct PCI/AGP dividers in some boards/chipsets, because MFers never knew Intel wouldn't release 166/667 desktop CPUs. Taping over a pad is meant to enable it. Useful to make settings more granular, modular, interactive-odular. Or because it's a huge leap between 533 and 800 if you've got 533 CPUs. 533 to 800 is possible but you need a low multi (slow) 533 CPU that's practically perfect.
Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.