the fsb is not integrated into the chip. there is no fsb at all.
current PCs (aside from the A64) use an fsb. That is a 64-bit wide path going from the cpu to the memory controller. The memory controller is part of the northbridge. The northbridge is one-half of the chipset. The other half is the southbridge. bits go up and down those 64 super-skinny wires which are built into the plastic of the motherboard to connect the cpu to the northbridge. Those 64 wires are called the fsb. bits go each way on them.
On an a64 the memory controller is built into the cpu itself. Its called an integrated memory controller, or an on-die memory controller - same thing. In order to identify what on an A64 is analogous to the fsb on other cpus, you have to examine the path between the on-die memory controller and the cpu. That path is still 64 bits, but it runs at the core speed of the cpu itself. In other words, its so fast as to be irrelevant, since bandwidth is always as fast as its weakest link, and the a64 memory controller-to-cpu path will never be a weak link.
The benefit of this memory controller is that the data no longer needs to make a pit-stop at the northbridge, which is known as latency. It also is a one-way path to the memory when outbound, with a separate one-way path when inbound. This also reduces latency. So on an a64 the bits flow more freely without having to stop and wait. This makes it better. ghz and bandwidth ratings only confuse the issue, its the reduced latency that makes it better.
