Mac Pro Westmere Conclusions
The sweet spot
For most users, the “sweet spot” is the 3.33GHz 6-core model. Upgraded to the MPG Pro Workstation it can really sing, because a balance is required to reliably exploit CPU performance: memory and fast drives.
12 cores is a mixed bag
The 12-core model sounds promising (at huge cost), but paradoxically can result in impaired performance with Photoshop CS5. On the other hand, it offers a big step forward with well-written programs, such as Photozoom Pro, or Logic Studio or Bibble Pro.
The quad-core models
For those looking to keep the cost down, the reality is that for most tasks, the 4-core models running at 2.8GHz or 3.2GHz are solid choices. And 6 months or a year from now when CPU prices drop, you can upgrade to a faster CPU.
Always consider total system cost before dismissing a faster CPU; think in percentages.
The 2.4GHz 8-core
The 2.4GHz 8-core model is a dud; at best it can only come close to the 3.33GHz 6-core model, with the sole exception of apparently more resilient performance with Logic Studio. However, the fact that it has 8 memory slots might make it a viable choice for specific purposes. For most users, ignore it.