temperature in celcius
E2XXX is better. 
E2XXX can reach 4G? i seriously doubt that 
i bet you will hit FSB wall before you can reach there 
and you need a good stepping E2XXX for sure
these F3 can hit 3.5G-3.6G with air cooler
for me i can do 3.6G with air
these F3 is for those people who using brisbane, adi hit the wall,
and looking for cheapest upgrade solution
or for those people who plan to reserve their am2 mobo until K10 price drop
if you are assembling new rig, you can just pick EXXX + any intel mobo.