That is a question that I am asked quite often. Pretty much any time someone complains their computer is running very slow, or they have had a problem with the monitor and have since replaced it to a larger one when the old one died. Yet the computer is still working.....
To answer this quite simply, it starts with the hardware the computer was built with. A very sturdy and reliable power supply is probably the first thing. That being said, no matter what computer you have, it is important that you use a UPS (Uninterrupted Power Supply) so that it takes the brunt of all power fluctuations that cause most of the problems with the computer. Since it starts with the power, having that good power supply can make your computer last many years.
So how many years can I expect it to last without any problems?
I always suggest using a 5 year plan. For the first 3 years, with routine maintenance which includes regular software updates, patches and optimizing of your system from malware/spyware and other viruses. Then keeping your unit free and clear of the dust bunnies that like to make their home inside, binding those pet hairs around the cooling fans. This resulting in slower than normal running fans which can lead to overheating and eventual failure. You don't need to open the box at all. This can be remedied with a swiffer duster regularly and every once in a while, a can of compressed air and a vacuum. With the vacuum turned on and pointing at the rear vents of the computer, blowing the air in to the power supply fan and system/case fan vent holes will get the dust flying and sucking it straight in to your vacuum.
Getting back to that 3 and 5 year plan.. 3 years if you haven't had to replace any major components such as power supply or hard drive then you are doing well. It is expected you may have to replace one of these within 5 years. However, within that 5 years you will have most likely gone through at least one change of operating system, if not two. The newer the computer, the more likely it will be upgraded to a newer operating system even more often. Now that Microsoft is working on getting a new one release every year, much like Apple has done for many years, you should expect within that 5 years, to have used 3 different operating systems.
I recently visited with a client that asked how old her computer and I figured it was nearing 5 years. She figured more than that. Looking at the records she will have had the same unit for 8 years this coming July! Amazingly, without replacing the hard drive or power supply! It originally was built when Vista was the rage and fortunately for her, because Vista was a real memory pig, it was built with lots of memory which made the release of Windows 7 a no-brainer. Because she was on Windows 7 without any incidents, she never did move up to Windows 8/8.1 however if her system is till working this fall when Windows 10 is released I will be certain to be upgrading her.
Realizing that this one incident which blows my theory of 3 to 5 years out of the water, but quite simply put, the components/motherboards are just not made the same as they were in the past. With processing speeds much faster these days, things are optimized to higher standards which means failure rates are higher as well. Fortunately the cost over all has dropped to the point where any component that is going to cost over $150 to repair is simply not worth it since you can now buy a new computer, complete with the latest operating system for less than $400 which means if you are spending about 40% of the value of a new computer to fix an old one that has at least one generation of operating system behind the current one then odds are you are probably going to start replacing other components on that same unit soon enough as well, so it is best to move to a new unit.
