Upgrading the hard drive
Solid-state disk (SSD) technology promises a dramatic decrease in hard-drive latency.
In our tests, moving from a 500GB, 7,200rpm hard-disk drive to a 120GB SSD resulted in an 8 percent general boost and an 18.4 percent speed jump for gaming.
SSDs aren't cheap, and you lose a large amount of your storage capacity in the bargain (nearly 75 percent, in our case). Still, presented with prices of £21.25 for each percentage point of general performance improvement and £9.24 for each percentage point of graphics improvement, power users may find the outlay worth their while.
Upgrading the graphics card
No mystery here. Upgrading to newer graphics will do wonders for your gaming. When we upgraded our older PC to an ATI Radeon HD 6870 card, gaming performance improved by 14.9 percent. With our newer Dell, an ATI Radeon HD 6850 gave us a 117.2 percent boost in gaming. But neither improved general application performance.
On the three-year-old system we needed to spend £10.06 for each percentage point of improvement, but the Dell's extremely low £1.11 for each percentage point of gain makes the graphics card upgrade on that PC the most cost-effective upgrade in our round-up.
You're likely to fare even better if you upgrade components in combination. Performing all four of the upgrades on our list - CPU, RAM, hard drive and graphics card - on our old desktop PC improved its system speed by 67.1 percent and boosted its gaming performance by 166.3 percent.
We also spent more, but the overall improvement was far greater than the sum of the improvements from the individual upgrades. Ultimately we spent £8.48 for each percentage point of general performance improvement, making the four-component upgrade surprisingly good value.You don't have to upgrade everything to see a boost, of course; your best bet is to focus on performance bottlenecks.
To find them, go to the Windows Performance Information and Tools Control Panel. Focus on the lowest numbers listed in the panel's Windows Experience Index, and upgrade your hardware accordingly.
Does it make sense to perform multiple upgrades when you could simply buy a new PC? Even under the best conditions upgrading is a hassle, and it gets expensive depending on the CPU: we spent about £400 to £500 to buy the components for our three-year-old PC upgrade. That's more than some new machines cost.
Effort and risks aside, it still makes sense to upgrade in some instances. Graphics are a sore spot here, as new computers with integrated graphics fared extremely poorly in our gaming benchmarks. If you want better games performance than your current system provides, focusing on a better graphics card makes more sense than buying a new rig that uses integrated graphics.
General productivity programs were a different story. We had to spend several hundred pounds on an overclocked 3.3GHz Core i5 PC with 4GB of DDR3 RAM and a 10,000rpm hard drive to substantially improve on the gains we saw from our CPU upgrades alone. In that case, investing in a new computer would have made more sense; for almost everything else, selective upgrading would have been the wisest choice.