Slashdot Mirror
Looking at Intel's New-ish Desktop Socket, LGA 1366
Slatterz writes "LGA 1366 is Intel's first new desktop socket in four years. It uses the same ZIF design as the familiar LGA 775 architecture, but it incorporates many more contacts. These big architectural changes are backed up by some less visible advances. Until now, Intel's quad-core processors have been constructed from two dual-core dies, but now Core i7 brings together four cores on a single die. It's also Intel's first processor design to use an L3 cache, shared between all four cores."
About time they copied HyperTransport! If I remember correctly AMD had a leg up on Intel for a few quarters in the multi-core war because of HyperTransport.
Please refer to the excellent Anandtech preview article on Lynnfield that will be the first family of CPUs to use LGA 1156. Lynnfield has uses a dual-channel DDR3 controller instead of using triple-channel integrated memory controller in its uncore like Nehalem does. However, the dual-channel controller should still provide enough bandwidth for most desktop apps (the Nehalem architecture is not bandwidth constrained at all, unlike all previous generation CPUs including Core2 that used massive L2 caches to offset the memory bandwidth bottleneck due to the FSB).
However, the main difference between Lynnfield/LGA 1156 and LGA 1366 used in servers is the fact that it doesn't use QuickPath at all. Instead, it uses a combination of integrated PCIe 2.0 x16 controller (to talk to the graphics subsystem) and a (much slower) DMI controller to talk to everything else. Its an interesting alternative to QuickPath which is frankly expensive overkill for desktops anyway. The key advantage of the new socket will be significantly lower prices of motherboards and CPUs, which will allow Intel to provide some credible alternatives to AMD's current offerings that may be slower than Nehalem but are also much cheaper.
The socket for Core i7 equivalent Xeons is the same LGA-1366, but the standard Core i7 only has one QPI link, so you can't use them in dual CPU configs.
I hadn't heard about LGA-1156, but I'm a bit suspicious whether it will really take off. I don't really understand now that Intel have launched LGA-1366 where is the room for a slightly lower spec socket. I wouldn't have thought a few extra pins in the socket is that expensive, and buying RAM in packs of 3 isn't that much of a problem - and it's optional anyway.
By Q3 when LGA-1156 is due, Core i7 will be already heading down into the mainstream.
Thanks for the correction. Yes, I meant to say that Nehalem is not bottlenecked.