same here with the m4a79t bios, been able to hit 4ghz stable on my 1055, also running 4x2GB mem at 1600 with 7-6-6-18-24-1t pretty stable with 2700NB, about 5 hours into prime95.

I actually had to change turbo on, set it to manual and change the multi to what my multi was set to, then turn it off to successfully post though, tried changing voltages and all sorts of things I guess it just didn't clear the settings correctly, no big deal though seems rock stable now with 300FSB