Its worth mentioning also that x86 64bit CPUs still use PAE, in fact they have to, its mandatory in long mode ("real 64 bit mode"). Additionally the version of

Its worth mentioning also that x86 64bit CPUs still use PAE, in fact they have to, its mandatory in long mode ("real 64 bit mode"). Additionally the version of PAE used in 64 bit mode is an extension of the original 32 bit PAE, adding an extra directory layer to support up to 52 bits of physical address space. Although i don't think any processor has implemented more than 48bits of address space so far.