There are many factors that can determine the lifespan of your computer, but one of those that you should pay attention to is dust.
This single substance can wreak havoc in a computer, which is why machines should be regularly serviced to remove build-up of dust in vents, on cables, fans and heatsinks. The internal airflow of your computer should be such that the processor, graphics card and motherboard are kept cool – if this is not possible, performance issues will occur.
A computer should be positioned in a ventilated area, one which is relatively cool and largely dust free. You should also avoid covering the vents on your computer.