[bryanlarsen]

Intel's newest Xeon processors no longer work with the consumer chipsets such as X99, a Xeon class chipset must be used. If Intel was going to release a new chipset for Xeon, they would have released it with the E5 v4 last week.

It's quite possible Apple was waiting for E5 v4 and is still waiting for AMD Polaris or nVidia Pascal, though.

[walshemj]

Some people actually prefer the workstation class mb and there ones designed for use in place of x99