There were four basic materials that the Egyptians used to build the pyramids: limestone, pink granite, basalt, and alabaster. Each type of material had a diverse use. Limestone had, for the most part, two uses.
To answer your question: The useful lifespan of a CPU is about 3-4 years. My guess on the technical lifespan under full load is closer to 8-10 years if nothing else breaks and takes the CPU with it. The reasons: High Performance Computing Clusters usually keep the computers for 3-4 years.
Here what I got on internet for you. Actually this solely depends upon you,how you use your machine. As a rule of thumb, the hardware in adecent laptop will be up to date for. two years, and the laptop can be expected to have a lifespan of 4 years.