Yorkfield vs. sandy bridge

Yorkfield was an amazing chip, I still have 3 computers based on them and a 2 based on Kentsfield.

There are far too many differences to list them all but I'll name the big ones

1. Kentsfield and Yorkfield are native dual-core dies. Each Kentsfield and Yorkfield processor was actually 2 Conroe or Wolfdale chips glued together. This means that each 2 processor block shared half of the total L2 cache and communication between the two processor blocks was problematic. Nehalem, Westmere, Sandybridge and Ivybridge are native quad and octal core processors (the 3930k and 3960x have two cores and 5-8MiB of L3 cache disabled for yield purposes) with unified cache. This improves cache access and interprocessor communication

2. Beginning with Nehalem the memory controller was moved from the northbridge onto the CPU itself. This reduced the nasty bottleneck that could be caused by the Front Side Bus, lowered latency by by necessitating only a single bus transfer rather than two, and greatly expanded the memory capacity in multi-socket systems.

3. Beginning with the mid range Nehalem processors (800 series and below) PCIe lanes were made available directly from the CPU. The first generation i7s still pulled them out from the northbridge only. Subsequently all Sandybridge and Ivybridge processors made 16 PCIe lanes available directly from the CPU and an additional 8 available with the standard 6 and 7 series chipsets. The on-chip PCIe lanes reduce access latency.

4. Sandybridge also included a ton of front-end improvements to the branch prediction and decoded instruction cache. These improvments also allowed for Hyperthreading to be reintroduced which allowed for unused back-end resources to be shared with different front-end threads. This improves performance by reducing idle time and causes confusion in those who don't know the difference between a thread and a core.