Reusing computer parts has a lot to do with the green lifestyle, but it’s hard to decide exactly how to proceed with every type of component.
The main principle is that a non-defective component should be used as long as possible, a period that is variable from component to component, because obviously there comes a time when a specific component is just not sufficient anymore. In the case of the hard drive, development was very fast in the past few years.

We have come a long way since the experimental refrigerator-sized 2.52GB hard drive from the 70s. Capacity, speed and power consumption have improved to a level which seems hard to beat. 2TB size, ~100MB/s average transfer rate and ~5Watt power consumption make the hard disk the second most power efficient component is the whole system, right after the DDR3 memory modules that need around 3Watts per module. The smallest and cheapest new hard disk available today may be enough for any operating system for up to 5 to 10 years, if we look at the evolution of space requirements in the past. Windows 7 requires around 16Gigabytes of hard disk space, Windows 8 most likely won’t require much more. Hard disk speed isn’t an issue, if you have enough RAM installed on your system.
For example an old fashioned LGA775 Celeron D 2.8GHz processor with 2-3GB of DDR1 memory can still handle flawlessly the most demanding version of Windows 7, when it comes to everyday office and home programs, although it was launched way back in 2005. With an appropriate graphics card it may also run some of the latest games with medium graphic detail settings.
The motherboard has a somewhat shorter lifespan, no matter how sufficient its speed still is. It includes most of the sensitive components of the computer system like ports (that have to withstand the user’s abuse, sometimes even electric shocks), voltage regulators and filters for the processor, slots (that also face some serious strain when expansion cards are installed)…etc. Motherboards most likely last around 3-5 years in a system in perfect, functioning condition. It’s not amongst computer parts that are worth reusing after a major system upgrade.

When you’re looking to reuse a processor, things get a bit complicated. Usually in 3 years or so the efficiency of a processor falls drastically, even if you bought a top processor back in 2007, today you’ll find that speed at half the price and also with increased efficiency. It’s not recommended to reuse computer parts like the processor and graphics card (that’s also basically a processor with a short life, because cheaper and more efficient ones appear on the market in every 1-2 years).

Although the computer case is a passive part of the computer system and may last many generations, it usually comes with an installed power supply that is not so durable. The cheapest power supplies work within optimum parameters for up to 2-3 years, after which they should be replaced with new ones even if they still seem to function properly. More professional power supplies (with prices above $100) should work perfectly for up to 5-7 years, assuming that you stay with upgrades under the maximum power consumption allowed.

Monitors are computer parts that are frequently reused. Some users still can’t give up their good old CRT because of its good picture quality and colors, no matter how much it hurts their eyes and how much power it uses. A 21” CRT from the year 2000 consumes 150-300Watts of power, while the latest 24” FullHD LED monitors need only around 20Watts to display a much bigger and sharper image. While monitors may work up to 10-15 years, they are not worth keeping more than 3-5 years, because cheaper and much more efficient models become available such a period of time.

Of course these are only some general conclusions, there may be some special brand computer systems out there that can be used and reused for up to 10-15 years, what’s your experience?













