Throughout this instructable, I'll give you some tips on how to select the right components for your energy efficient PC. Whether you want to build an ultra efficient power sipping Linux network device or a PC with enough power to play today's demanding games but that's light on both your wallet and the environment, you'll find advice here.
If you're not convinced all this is worth the trouble, read the next step for a counter argument to that.
note: I use the term PC throughout this article. While most of the advice only applies to PCs in particular (for example: most people aren't building a Mac from scratch, but you may be able to replace the hard drive or other components in Apple's machines), some advice applies to Macs just as well. The advice in steps 1 and 2 apply to just about any modern computer in existence.
Step 1: Why bother? Or, turn it off!
Turn it off! The most energy efficient PC is one that's off. Seriously! Many people leave their desktops on 24/7/365. If you're not using it, you're just throwing money down the drain. How much money? That depends on how much power costs in your area and what kind of PC you leave running. You can buy a device called a kill-a-watt that will help you measure the energy use of a device. They don't cost that much, and you'd be surprised how much energy things around your house suck up, sometimes even if they're "off". Next, open your utility bill or call your utility company to ask them how their pricing works. Once you know how much your PC uses and how much your electricity costs you can calculate how much money it costs you to run your PC constantly.
A recently released report concluded that US companies alone waste $2.8 billion a year powering unused desktop PCs. The average cost of running a single unused desktop PC? $36 annually. And these are business desktop PCs. If you're leaving your souped up gaming rig with its power sucking overclocked CPU running 24/7, you may stand to save a lot more.
Hey, you shouldn't do that! All that powering on and off will put wear and tear on your computer's components. Your hard drive will crash. Your mother board will fry. Your power supply will burst into flames. Your house will burn down. You'll be homeless and responsible for all the co2 emissions from your burning possessions. Actually, no. None of that will happen. Well, probably not anyway. Modern PC components are built to survive thousands of power cycles. That's not to say they won't fail eventually, but the odds are that powering off your computer when you're not using it won't make it explode.
In fact, there's evidence that indicates powering off your computer may actually be beneficial to its longevity. Components like desktop grade hard drives aren't designed to be used constantly. Using them 24/7 may shorten their life. When your computer is on, it generates heat. The more heat, the more likely component failure is. Also, any moving mechanical part of your PC will wear. If they are moving constantly, they will wear faster and fail sooner. Prime example, fans. If a case fan fails, the heat buildup inside the machine can cause component failure. If your power supply's fan dies, I would say that's even more dangerous. Not only could heat buildup inside the PSU kill it, it could dirty the power to other components and fry them too. If your video card fan dies, you'll start to see graphical artifacts from the over heating and it will eventually fry itself (this has happened to me twice).
I can't claim powering off your computer is guaranteed to lengthen its life. I can't even claim that keeping it powered on all the time won't do the same either. There's evidence on both sides of the debate, so I'll leave that judgment to you dear reader. What it will do though, is save money on your power bill.
Of course, you'll probably want to actually use your computer at some point. So let's talk about making it energy efficient when it's switched on.