Once your memory was enough to power your system, but application demands have risen

Memory has fallen in price, and that alone has made putting more RAM into our systems a realistic option. More memory means less time spent caching out to the hard drive, making your PC more responsive.

Memory pricing can still be volatile, but in general it has never been so affordable to upgrade. There is one exception to this rule, though – DDR3 memory. Despite old DDR2 dropping in price, the newer stuff's cost has stayed stubbornly high.

However, the relentless march of technology means that DDR3 will get cheaper. With all this in mind, we recommend that 4GB of RAM is the target for most machines, and if you're running a triple-channel Core i7, then go for 6GB. Going beyond this isn't a complete waste of money, although memory isn't free – so the current sweet spot is a 2 or 3GB upgrade.

Memory matchmaking

To make an effective upgrade, you should add an identical pair to your existing sticks – assuming that you have an identical pair in your machine already. So if you've got a pair of 1GB 800MHz DDR2 sticks running at 5-5-5-18 latencies, say, then ideally you'd buy an identical pair and drop them in alongside.

These sticks needn't be from the same manufacturer, but they do need to have the same latencies and operating frequencies. Matched capacities will also make life easier.

Most memory modules ship with a sticker on the side detailing exactly what their timings are, so physically examining the modules should be all you need to do in order to get the right sticks.

If you bought your machine prebuilt however, you may find that the sticker is missing, or is unreadable. Thankfully, utilities such as CPU-Z can reveal everything that you need to know about the memory in your machine.

If you're having problems, then online tools such as Kingston's Memory Search can help when it comes to spotting what memory has been used by some of the more popular system builders.

There is a problem with upgrading to 4GB of course, and that is the limit of addressable memory offered by 32-bit operating systems. Essentially, in any 32-bit version of Windows, you won't see the whole 4GB. The solution is to upgrade Windows to a 64-bit rendition. Happily this may not cost you anything, depending on your version of the OS.

How to: Pick and install the right RAM

1. Investigate existing RAM

RAM 1

Use CPU-Z to check your current memory settings. There are two tabs that you need to look at – Memory and SPD. The Memory tab shows how fast your RAM is currently running and what timings it's using. The SPD tab shows you what the memory stick in each slot is capable of.

The key factors here are the module size and the JEDEC timing settings for the frequency at which the memory is currently running. This information is given for each memory slot, and hopefully you should have some slots free.

2. Confirm the part number

RAM 2

CPU-Z will tell you what sort of RAM your machine is using, but it's worth physically checking before you order. Hold the memory at the edges and ease out the clips that hold the stick in place at the ends.

You should now be able to remove it and have a gander at its sticker. Just searching for the part number can be enough to find replacements, although this can mean you miss out on better deals.

You don't have to buy matched pairs for normal use, either – but make sure you get the same frequency and latencies.

3. Install, then check the BIOS

RAM 3

Memory installation is fairly straightforward, possibly hampered only by the amount of room in your case. If you need to unplug drive cables or remove the graphics card to get better access, do so – it beats damaging the memory.

Once you've populated the bays, restart the machine and head into your machine's CMOS configuration utility. You should find that the memory settings are fairly well signposted. Ensure that the timings are correct (use SPD timings by default), save the changes and restart your PC to get going.