With the processor market in a highly competitive state, Intel couldn't afford to sit still for long. So, it reworked the Core architecture to create Nehalem, which adds numerous enhancements. The cache controller was redesigned, and the L2 cache dropped to 256KB per core. This did not hurt performance though, as Intel instead added between 4-12MB of L3 cache shared between all of the cores. CPUs based on Nehalem included between one and four cores, and the family was built using 45nm technology.
Intel significantly reworked connections between the CPU and rest of the system as well. The ancient FSB that had been in use since the 1980s was finally put to rest, and it was replaced by Intel's QuickPath Interconnect (QPI) on high-end systems and by DMI everywhere else. This allowed Intel to move its memory controller (which was updated to support DDR3) and PCIe controller into the CPU. These changes significantly increased bandwidth while latency plummeted.
Once again, Intel extended the processor pipeline, this time to 20-24 stages. Clock rates did not increase, however, and Nehalem ran at comparable frequencies to Core. Nehalem also was Intel's first processor to implement Turbo Boost. Although the fastest Nehalem processor's base clock topped out at 3.33GHz, it could operate at 3.6GHz for short periods thanks to this new technology.
The last major advantage that Nehalem had over the Core architecture was that it marked the return of Hyper-Threading technology. Thanks to this and numerous other enhancements, Nehalem was able to perform up to twice as fast as Core 2 processors in heavily-threaded workloads. Intel sold Nehalem CPUs under the Celeron, Pentium, Core i3, Core i5, Core i7 and Xeon brands.