As world energy costs are on the rise, one really easy way to save some money around the home is to reduce your PC running costs. It is quite common for some people to leave their computer running 24/7, along with the connecting peripherals. If for example you have a high end PC and LCD monitor, you could be using up to 350W under heavy load and 200W when idle. If you have a CRT monitor these figures could be even higher. Assuming that the average load is 275W and you leave your PC on 24/7, the cost per year would be £241 (at £0.10/kWH). This figure doesn’t even include optional extras that may be left on permanently, such as routers.

Hardware manufacturers are even creating “energy efficient” hardware, with Intel creating a G0 revision of the Q6600 quad core processor that uses only 95W. The normal B3 revision uses 105W in total, which would cost more to run, produce more heat during use and have lower overclocking potential.

There are plenty of tips for reducing your PC power consumption, some obvious and others you might not know about. The power management tools on modern hardware and operating systems make it quite easy to reduce the cost of running your PC.

Reduce power consumption when not in use

Many people will leave their PC on overnight, just to keep a few documents open till the next morning. Fortunately, there are two simple methods you can use to get round this.
  • Hibernation mode creates a backup of your current memory contents (i.e. your computer state at a moment in time) and saves them to the hard disk. Once the backup is complete, your PC will power off exactly as it would if you shut down normally. However, when you turn your computer back on it will resume the previous state, allowing you to continue working on documents where you left off.
  • Sleep mode is a way of temporarily putting your computer into a low power state – sometimes called “stand-by”. This will still consume some power, but all non essential components are powered down (excluding the RAM). This is an ideal alternative to a screen saver, as the system state is preserved and normal operation can resume within a few seconds.
If you need to leave your PC on because you download files, then you can try using a download manager such as FDM or uTorrent (for BitTorrent files). Both of these have an automatic shutdown option so you can leave your PC downloading overnight, but once this is complete your computer will automatically power off.

Use the Windows Vista Power Options

Microsoft have released a whitepaper documenting their testing methodology and results of power consumption used when upgrading a fleet of Windows XP computers to Windows Vista. Incredibly, it claims that this saved anywhere from £23-£46 (approx $40-$90) per system per year!

This is primarily due to improvements in Windows Vista power management, which is an especially welcome addition for laptop users. You can access the Vista Power Options page by clicking Start > Control Panel > System and Maintenance > Power Options. You are then presented with several power plans, with the energy saving and performance details shown alongside:


Most desktop users would be best suited by the “balanced” plan, perhaps with some additional customisation. To do this, click on “change plan settings”:


You can then configure when the monitor is put into standby mode, and when the PC goes into sleep mode. If you often leave the PC for long periods of time it may be worth automatically putting the computer in to sleep mode after 30 minutes, as this will save a large amount of power and allow you to resume working from where you left off upon returning.

There are power saving operations going on behind the scenes, as some CPUs support throttling (such as the Q6600). This means that if you are doing a non CPU intensive task (such as running Minesweeper!), then you don’t need the full power of the processor. The speed will be automatically adjusted in the background to switch between different speeds depending on the power required at any particular time. The power savings from this do add up, especially when it comes to longevity of laptop batteries.

Be selective when buying hardware

Each piece of hardware comes with a different power requirement. Just looking at the PSU rating will not give a clear picture of the overall power usage, but you can make smart purchases to make sure you have the most efficient devices. Monitors are one component where there can be a huge variation in power consumption, as older style CRT monitors use far more power than an LCD alternative. It might even be cost effective (over period of several years) to swap frequently used CRTs for modern LCD monitors.

Gamers and high end enthusiasts don’t have as much of a choice, as graphics cards and CPUs are major consumers of energy. Generally speaking, the faster the component the higher the energy usage will be (from each new generation of hardware). There are some CPUs which are designed for low power consumption (usually for laptops, but also desktop systems) which may be worth considering if they are priced competitively.

Consider peripheral items

Most computers will have plenty of external hardware devices, such as routers, printers and speakers. Although they are only used at the same time as a computer, they are frequently left switched on permanently. The combined power consumption of all these devices in standby mode may only come to around 20W, but would save just under £10 a year if they were turned off for 12 hours each night. Not a very big saving, but it is “free” money just for the flick of a switch.


There are some quick, easy and free methods of reducing your power consumption highlighted in this article – which will save you some money for very little difference in the day to day operation of your computer. If you are using Windows Vista, it is extremely easy to tweak your Power Options profile to make sure your PC makes the most of sleep mode. Using hibernate is also an excellent way of preserving a Windows session whilst you are away from the PC. Changing hardware is a drastic way to reduce running costs, so the advice above would primarily apply to new computer purchases – allowing you to make an informed decision.

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Ian, Jun 18, 2009