I can deal with 533 but.... joefriday....are you saying it will only run @ 400mhz?
If you set the FSB to 533, then it will run at that speed. Initially it might boot at 400. It won't work only if the motherboard can't handle it at all. Why not get a CPU that works with your motherboard or get a used motherboard that supports that CPU?
I am fixing a friend's computer and I do not have the $$ to buy parts for the friend. I have several P4 processors and want to use the ones I have.
As GhislainG stated, IF you can manually set the FSB, either by jumper or through the bios, then the CPU will run at 533 fsb, but if you cannot, it will default to 400 mhz fsb, if it runs at all.