The simple answers is based on what you are trying to do. A great example would be a designer who models with Solidworks or Autodesk Inventor, and does some heavy rendering in Keyshot would need the following parameters:
- i7 CPU with speeds in excess of 2.4 Ghz ( this is really where you see speed gains in CAD since they are all single threaded)
- 64 GB of RAM to handle large assemblies
- 16 GB Video Card ( to handle large 3D scan files, but if you don't need 3D scanning capabilities then you can go for something much smaller, since the CAD programs do not utilize the GPU, even though they say they do ;)
I hope this gets you going in the right direction. My personal choice is the WS65 from MSI, here is a link if your interested
This MSI workstation has all the power and the portability that I need to travel.