Different dividers are part of different straps, and even then, different dividers within the same strap may not have the same ease of setting.

Generally, with p965's, 400fsb with 4:5, some boards have trouble as is. Beyond 400fsb and wanting to use anything but 1:1 or 2:3 is generally incredibly difficult.

If you're insistent on using 4:5 at 426fsb, you're going to probably need a ton of vmch to do it.