Need help w/ HyperTransport understanding

The HTT bus is amd's new and improved fsb. Memory access has been changed to it's own bus, while the HTT is faster, and is more bi-directional.
The memory speed will not likely ever catch up to the HTT bus, but having memory that is slower than the memory bus, does take a hit. The latest HTT bus is 1ghz each way, while the memory bus is still running at 200mhz, with DDR, for an effective rate of 400mhz. There is also dual channel, on s939, which doubles the potential memory bandwith.

I know its different for the XP chips (staggers latencies) but for the Athlon64/FX chips it might be the same as the P4 chips. Ask crash.

On the topic of the FSB, FSB is generally used to tell us the speed that the CPU connects with the northbridge.
Since the Athlon64 range of CPU's doesnt have a northbridge (its memory controller is on the CPU instead) then technically it doesnt have a northbridge. Instead it has a southbridge where all the peripherals are connected (PCI slots, USB, AGP etc) This southbridge is connected to the CPU Hypertransport link. The memory is connected to the CPU on a different bus.

You will ofter hear that the hypertransport link runs at 1.6Ghz-2Ghz. This is a marketing slogan, it if fact runs at 800Mhz-1Ghz but it is FULL DUPLEX. This means it can send data in both directions at the same time. The intel pentium4 bus is only half duplex.

- Some more info <A HREF="http://forums.amd.com/index.php?showtopic=11141" target="_new">here</A>.

- DDR500 wouldn't be a requirement.