Pentium 4 socket 478 info?

I have an older PC running a Intel D865PERL motherboard, my question is, what is the fastest processor I can buy for this board? I checked the doentation and it says 3.0 Ghz 800 FSB. I went online and the processors go as high as 3.4, but I've also read that these socket 478 chips somehow don't fit my board. Is this true? Can I go higher than 3.0?