Thanks to Buck_Naked from our forums to alerting me to this information on AMD's 90 nanometer Athlon 64 processors (there a link to benchmarks as well):

* Full SSE3 implementation
* Improved hardware data prefetch mechanism
* Increased number of writing combine buffers (D0 stepping A64's can now combine up to four non-cacheable streams compared to 2 o­n the C0 and CG stepping A64's)
* Improved o­n-die memory controller with more advanced open page policy
* O­n-die thermal throttling
* Black Diamond Low-K technology (slower less power hungry transistors in less used sections and faster and more power hungry transistors in frequently used sections of the cpu)