The Cooling Fans
A PC generates a lot of heat and heat is a major enemy of electronics. So it is important to keep your PC running cool. Most PCs employ a combination of heat sinks and fans. All power supplies incorporate a fan. Most CPUs have a heat sink and a fan. Many PCs have another fan inside the case to circulate air, graphics cards may have a built-in fan and some have fans just for cooling the drives.
Fans help to carry away excess heat, they are vitally important for the health and longevity of your PC. If a fan slows down or fails completely, the PC or a specific component will begin to overheat. Although the PC will continue to operate, it will shorten the lifespan of all affected components. When a certain temperature is reached a PC may shut itself off automatically. It will not restart until it has cooled sufficiently. In some cases, overheated components will be destroyed and will have to be replaced.
Because these fans have moving parts and they run the entire time the computer is on, they will wear out. It is not uncommon for a fan to wear out in just one year, although many run for years.
If a fan in your PC stops running, it is critical that it be replaced. Your PC will run without an operating fan, but possibly not for long. It is never wise to run the PC if there is a possibility of overheating. A system that overheats may malfunction, shut itself down or components may be destroyed by the very high heat. Fortunately, fans are inexpensive and relatively easy to replace.
While the fan inside the power supply might not be replaceable, the entire power supply can be replaced. The cpu, case and drive fans are also replaceable. A graphics card fan may not be replaceable if it is integrated into the construction of the card. In that case, contact the manufacturer for information on possible repair.