My 2x E6850 L723A347 cpus on Asus Blitz Formula 1101 with Corsair Nautilus 500 water cooling:

E6850 L723A347 #1
VID: 1.325v
Max boot into memtest86+ v1.70 at 1.296v default vcore = 3933Mhz
Max FSB = 485-487FSB
Max CPUZ Validation = 4374Mhz - 9x486FSB at 1.712v
3006Mhz = 1.192v Prime95 v25.3
3600Mhz = 1.336v Prime95 v25.3
4000Mhz = 1.472v 32M
Max 1M = 4338Mhz at 1.712v single core, 4323Mhz at 1.632v dual core
Max 32M = 4266Mhz at 1.712v single core, 4158Mhz at 1.632v dual core

vs

E6850 L723A347 #2
VID: 1.3375v
Max boot into memtest86+ v1.70 at 1.296v set vcore = 3897Mhz
Max FSB = 530-535FSB
Max CPUZ Validation = not yet tested
3006Mhz = 1.168v Prime95 v25.3
3600Mhz = 1.304v Prime95 v25.3
4000Mhz = 1.472v 32M
Max 1M = not yet tested
Max 32M = 4104Mhz at 1.632v dual core (even 1.68v-1.712v vcore didn't help 32M pass at 4158Mhz single core or dual core enabled)