You can sync your RAM 1:1 because your FSB is also 400. Then start working on the timings, you should have no worries getting CAS 3 and tight timings, could even pull your subtimings down if you really want to tweak it. Auto Vcore is about 1.27v anyway and I doubt it would raise to over 1.3v unless you set it.

Set your RAM voltage manually to 2.1v before you try reduce timings, or overclock it.