After flashing bios on my P5a from 1007 to 1007a, my carefully achieved setup (k6-III 400@472, 4,5*105, 2,4@2,9v) wouldn't work. In fact the best result I would get was 450, while with my old bios I once reached 500 (unstable though). Wondering what's causing this.

Has anyone by the way achieved 500mhz or more with a K6-II 400 ?