Differences between Socket 940, Socket 754 and 939?

[Manzelle]

What are the exact differences between Socket 940, Socket 754 and the upcoming Socket 939. I know 939 will not require the registered memory but that is all I know. Will it be dual channel? Will a 940 chip work in the 939 motherboards? Can someone help me out or provide me with a link that will explain the differences. Thanks.

 

[Peter]

Socket 754: One RAM channel, no extra HyperTransport links for multiple CPUs.
Socket 940: Two RAM channels, HT for multiple CPUs. Both RAM channels come out the same side of the CPU, to allow dual boards to fit on EATX footprint. This however requires registered RAM.
Socket 939: Two RAM channels, single CPU. RAM channels are arranged left and right of the CPU, eliminating the need for registered RAM.

 

[XBoxLPU]

Also with the introduction of the 939, HT will be upgraded to 1000mhz

 

[Peter]

250 MHz 16-bit-wide bi-directional, actually. To the marketing folks, that's 1000 MHz. To a tech hat guy, it isn't