The E6850 will be the fastest model, with a clockspeed of 3GHz and a FSB of 1333MHz:
All the CPUs have the same specs that includes 65 nanometre core based on Conroe CPU, 4 MB of cache memory Intel V-pro 2007 and a new architecture called Intel TXT.Details about what the Intel TXT stands for aren't known yet.
The second in line will end up with E6750 brand and it will work at 2.66 GHz, third is E6550 a new CPU clocked at 2.33 GHz and the last is called E6540 that works again at 2.33 but doesn’t supports TXT.