CPU is considered the most important element and heart of motherboard. It’s architecture has evolved from 8086 days to the current Skylake architecture having the multiple cores.
Main goal of CPU architects was to reduce power consumption and die area required. There are many architectural and microarchitectural changes went into CPUs over the years. The main architectural changes goes into pipeline and cache level architecture which helps improving the performance.
8086 processor had 16-bit address bus and 8-bit data bus. It was single core architecture. Single core architecture does not contribute to performance a lot. Also, instruction pipeline had only 5 basic stages which provides the simple parallelism. The motherboard had separate northbridge which connects to system memory and southbridge which connects to IO’s. There was single level of cache architecture having small amount of cache which was providing small amount of performance enhancements.
Over the period of time, drastic changes were required in the CPU and platform architecture in order to get the maximum performance. Also, reducing the power consumption on platforms was one of the basic requirements. Drastic changes done into Pentium processor architecture in order to have more performance. It was multicore architecture having the multilevel of caches, adding more stages in pipeline and coherency protocol to maintain cache coherency in an architecture. It allowed huge amount of performance enhancement via CPU. Pentium architecture came with many new CPU instruction which can enhance the feature capability of CPU. SSE and MMX instructions allowed programmers to do complex arithmetic operations on CPU which can help doing computation faster. There were changes done to add the low power states in an architecture which can help save power on platforms. Still, There was out of the box thinking was needed to change the way computer was used completely. There were many architectural and micro-architectural changes were needed in terms of having the good performance and saving the power on platform. Multi-Core and Multi-Threading architecture was needed to improve the performance.
The biggest breakthrough in platform came during latest sandy-bridge architecture in which motherboard had two-chip solution instead of three-chip solution! Northbridge was moved completely to the same die as CPU. It had three level of cache and on die shared bus which can carry large amount of traffic. There was big change in CPU architecture having shared caches and multiple cores which can add to parallelism on platforms. Shared bus which can share data between caches, cores and northbridge having the large amount of capacity to carry huge amount of traffic between components. Also, having the three level of cache with robust MOESI protocol which helps in coherency. There were many new floating point instructions added in an architecture which helped doing complex operation.
Sandy bridge was followed by the Ivy bridge which was process shrink and provided more performance compared to its previous version. In conclusion, CPU has evolved over the years in terms of architectural and micro-architectural changes to have performance enhancements and reduction in power consumption.
