I think that AMD?s 4X4 tech is supposed to beat Intel to the punch on home user quad core processing, mainly from a marketing point of view. From what i have read Intel plan to debut Kentsfield as the next s775 Extreme Edition processor, over the current x6800. This will be a single socket dual die processor, where as AMD plan the same thing but with two separate sockets for the two dual cores ala 4x4 (this much we already know).
I don?t think there will be any difference between the two other than Intel having the upper hand due to the new processing cores that will be used, aka 2 x Conroe cores, and obviously the difference in subsystem I/O of today.
So AMD will probably try and claim that they are the first to bring Quad core processing to the home user if they beat Kentsfield to launch.
Now I have also read that the two FX?s that are required for 4x4 to operate, has been projected to cost the same amount or near enough to what a normal single FX in the past has cost on release. So on a price basis AMD should be somewhat competitive to the Kentsfield EE. AMD by then will be manufacturing on 65nm, so this should balance costs compared to today?s 90nm manufacturing cost, aka to help make the lower cost possible for the end user when buying two FX?s. However at the time Kentsfield might have the upper hand, due to the fact current motherboards are said to be able to support Kentsfield. Not to mention Kentsfield?s superior processing power. And with AMD?s 4x4, you will obviously have to purchase a new mobo however much that will cost, so no obvious upgrade path. I have also read that AMD intend to produce the chipset for this 4x4 tech, instead of the likes of ATI or nVidia, however they will most likely out source the core logic.
The issue will still remain that even though AMD will perhaps have a speed bump from 65nm, they are still using the inferior K8 design compared to Intels superior Conroe/Kentsfield.
As we already know K8L will be the first single die quad core processor, along with all the new tweaks that will warrant its new core name, K8L. So from my POV, AMD plan to just hang in there until K8L arrives.