Ok, testing QX6850 with BX2 rev 504 and work ok, with 2777 bios. Max stable FSB is around 390MHz with 1.6-1.65Vmch - more do nothing. Weired is when I testing this combo under cascade and set 13 x 380MHz ... mobo boot easy, in bios correct freq, but in windows I have still 13 x 333MHz grr. Sometimes mobo change mem freq from 4:5 to 2:3, but after changing manualy in bios to 4:5 and boot freq of mem is ok.

My two cents

Martin