In spite of the fact that AMD was the first to announce development of its dual core CPU, Intel was first to the market with its dual core Pentium Extreme Edition 840 CPU. This processor, like AMD’s first Athlon dual core, was manufactured with a 90 nm fabrication process that had some heat and power concerns, but offered incredible computing power for the desktop. The architecture of this CPU differed from the first dual core Athlon’s in that it required an external memory controller. Also, the cores of the Extreme Edition 840 communicated with each other through the relatively slow Front Side Bus.
Although this CPU fit the same LGA775 socket as its Pentium 4 counterparts, they were not a drop in replacement for the older Pentium 4 chips because the new CPU required a new chipset. This forced the purchase of new motherboards by customers desiring the new technology, slowed adoption of the Intel dual core processors, and set the stage for AMD to make a strong showing when its Athlon 64 dual core CPUs finally came out. Intel’s dual core CPUs were fitted with a shared 2 MB L2 cache that gave it an advantage over AMD’s offering that had a smaller, dedicated cache for each core. The shared cache was not only larger on a per core basis than AMD’s Athlon dual core, but also was accessible by each core, enhancing the CPU’s performance with single threaded applications.