How do PCI-E lane limits work in a CPU?

[JacoFett]

Say the 5820X supports PCI-Express lanes and the 5960X supports 40 lanes. How is this limit determined?

 

[Ecky]

I'm sure both CPUs are made of the same silicon, Intel just disables some on the 5820X for market segmentation, and discounts it.

Very much like how an FX-4300 has 8 cores, but AMD just disables 4 of them.