Eco-friendly PCs: An inconvenient upgrade path

Look outside your window. See all that lightning, thunder and flooding? That's global warming in action, we tell you. It's supposed to be summer, but autumn has jumped the queue, hinting at a time when we'll all be under 30m of snow -- like that film The Day After Tomorrow.

If you ever want to see a rain-free Wimbledon again, you'd better start getting your hippy on. To help, we've rounded up a clutch of PC upgrades that we reckon could help reverse climate change and save you money on electricity.

Processor
When choosing an environmentally friendly processor, you should look for one with as low a thermal design power (also called thermal dissipation power, or TDP) as possible. This is the maximum theoretical amount of power (in Watts) that a processor may consume and therefore dissipate as heat. A chip with a low TDP will consume less electricity than one with a comparatively high TDP.

Intel has promised a CPU that it claims will run on "a median average" of just 0.75W, but this is some way off. In the meantime we'd recommend using a laptop CPU in your desktop (you'll need a compatible motherboard) as these are designed to be more power-efficient. The Intel Core 2 Duo L7400 processor has a TDP of just 17W. Compare this to the 65W TDP in the 2.13GHz Core 2 Duo E6400 desktop CPU and you can see the potential benefit immediately. Sure, the L7400 runs slower, but it's a dual-core processor where each core runs at 1.5GHz, so it's fast enough to cope with most everyday tasks. There are processors with a lower TDP, but we think this is a good balance of performance and tree preservation.

Graphics card
People forget how much harm can be done by a graphics card. It's the part of the PC that should bring most joy, but it's a killer, honest. The best thing you can do, ecologically speaking, is buy a motherboard that has an integrated graphics card. These won't let you play many games, but at least you'll have a planet to live on. If you really must kill aliens in Doom 3, go for an MSI Nvidia Fanless 8600GT card (£95), or better still, an MSI Nvidia Fanless 7600 GT (£80), if you have an AGP slot on your motherboard. The latter has a graphics processing unit with a 400MHz clock speed, and does not need an extortionate amount of extra electricity from the PSU (see below). It's a far cry from the electricity-guzzling, planet-murdering 1.35GHz-rated Nvidia 8800 GTX.

Power Supply Unit
It's easy to get carried away with big numbers -- but the less electricity consumed by the CPU, graphics card and the rest, the less juice the power supply unit (PSU) needs to provide. A 1,000W PSU is overkill for most of us -- you should opt for something feebler, such as a Zalman ZM360B-APS ATX Noiseless PSU. This 360W model is powerful enough to drive your components without simultaneously killing Mother Earth and her 6.6 billion children.

Solid-state drive
If you've still got any money left, we recommend swapping your standard IDE hard drive with a solid-state drive (SSD). Samsung's first SSD, a 32GB model, is said to use just 5 per cent of the energy it takes to run an ordinary hard drive. They're not particularly large (up to 64GB is currently available), and they're not easy to get hold of, but they offer faster file-access times than your old hard drive and may help preserve that ozone layer thingy in the sky.

Monitor
Our final bit of advice is to recycle your old CRT monitor with a company such as PC-Solutions. CRTs consume far more power than thin-film transistor (TFT) or flat-panel screens. While you're at it, look for a monitor that conforms to RoHS Directive standards. This stands for the "restriction of the use of certain hazardous substances in electrical and electronic equipment", and basically means the monitor isn't made out of bad stuff: lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl and polybrominated diphenyl ether flame retardants. Nature hates this stuff more than kids hate broccoli.

Once you've finished upgrading, we recommend doing simple things like switching off your PC (and your monitor) when it's not in use, buy refurbished parts if possible, enable the power-management features in your BIOS, don't print anything you don't really need to, and donate your PC to charity when you're done with it. -Rory Reid