even with standard water cooling my 2.8e seems to max out under 3.4ghz (even with as much as 1.62v)
i think i just got an early stepping tho
4ghz is what most people woulda liked to see outta their 2.8e purchases, but you'll need really good cooling
with good air cooling people have gotten them between 3.2 and 4ghz
just a matter of luck i guess, but i hear the later steppings are doing good