Anand Lal Shimpi from AnandTech discusses the cache of the Nehalem, the mainstream LGA1156 processors and the 32nm future processors from Intel.
Now we’ve got an exponential growth of cache size, not linear, and all of the sudden the Core i7 conforms to societal norms. To understand why, we have to look at what happened around 2005 - 2006: Intel started shipping dual-core CPUs. As core count went up, so did the total amount of cache per chip. Dual core CPUs quickly started shipping with 2MB and 4MB of cache per chip and the outgoing 45nm quad-core Penryns had 12MB of L2 cache on a single package.
The move to multi-core chip designs meant that the focus was no longer on feeding the individual core, but making sure all of the cores on the chip were taken care of. It’s all so very socialist (oh no! ).
Nehalem was designed to be a quad-core product, but also one that’s able to scale up to 8 cores and down to 2 cores. Intel believes in this multi-core future so designing for dual-core didn’t make sense as eventually dual-core will go away in desktops, a future that’s still a few years away but a course we’re on nonetheless.