Sorry, I didn't meant to imply the Z620/820 supports v3. Just pointing out that the performance jump in Sandy Bridge was significant. v1 and v2 are socket comp

Sorry, I didn't meant to imply the Z620/820 supports v3. Just pointing out that the performance jump in Sandy Bridge was significant. v1 and v2 are socket compatible, but v3 is not socket compatible with the earlier versions, but will likely be compatible with v4 (Intel socket changes usually happen only every other generation). I'd suggest going all new with even a low end E5 2620v3 if you can, which you could for everything other than the GPUs for under 1700 (based on a Supermicro workstation build).