Running CAD, which one would perform better assuming they had the same amount of ram and same gpu?

6700k would be a better choice in this situation. Pretty sure the IPC will trump the 8 physical cores at that low of a clock speed.

OC the 6700k to a good 4.6-4.8 and you'll be gucci.

yes in most cases, depends on which type of cad though, but most modern cpus do great

I guess that's true. 3D modeling or 2D?

I believe it would be 3D. They also run solid works