FYI, the HyperTransport link in a modern AMD system is conceptually similar to the FSB (front-side bus) in Intel or older AMD systems. But HyperTransport is more sophisticated and you can have multiple channels I think so different subsystems won't necessarily congest each other unlike a FSB.
From: http://reviews.cnet.com/processors/amd- ... 08353.html
a little info about HyperTransport speeds:
"The X4 9850, though, features some more technical improvements over the lower-end models, and not just a faster core clock speed. Like the Phenom 9500 and 9600--and past AMD chip designs as well--the X4 9850 has a built-in memory controller regulating the speed at which data moves between the processor and the system memory. It also relies on the HyperTransport 3.0 standard, which links the processor to the various other components in your system, such as the PCI-Express data path for graphics processing. The memory controller and the HyperTransport clock in the earlier Phenom chips came in at 1.8GHz and 3.6GHz, respectively. The Phenom X4 9850 received boosts to 2.0GHz on the memory controller and on HyperTransport to 4.0GHz."