BOOT CAMP 409 (31/01/06)

Upgrading your PCs memory, part 1

It hardly seems credible now but back in the early to mid 1990s one-megabyte RAM modules were selling for £50 and were in such short supply that there was a sizeable black market in stolen memory chips. Unscrupulous manufacturers routinely sold PCs with inadequate memory, sometimes barely enough to run the operating system let alone any applications, but it allowed them to reduce the headline price and stimulate a healthy demand for costly upgrades.

For the past few years, since the introduction of memory-hungry Windows XP, most PC makers seem to have got the message about equipping their machines with a reasonable amounts of RAM as standard. The increased demand for computer memory has helped drive down prices and apart from a few brief periods when chip factories closed or burned down there continues to be a plentiful supply.

Nevertheless there are still some computer manufacturers who cut corners with memory and most Windows XP PCs with 512Mb or less RAM generally benefit from an upgrade so over the next few episodes of Boot Camp we’re going to be taking a close look at computer memory -- what it is and what it does -- and how to give your PC a quick, simple and cheap performance boost.

Basically RAM or Random Access Memory is where your PC stores information that it needs to get at quickly. It can be just about anything from the applications you are running to the web page you are looking at now. Fortunately there’s no need to delve too deeply into the technicalities of memory but it is worth knowing that RAM is a ‘volatile’ type of memory. In other words, unlike non-volatile ‘Flash’ memory cards used in digital cameras, pen drives and MP3 players, it only stores data for as long as it is connected to a power source.

However the key feature of PC RAM is that it very fast, blisteringly fast in fact -- compared with other data storage devices, like hard drives, optical discs and so on -- and this has a direct bearing on how quickly your PC can do things. You can also take it as read that the more RAM that you have the faster your PC will go. When Windows is short of RAM it wastes time shuffling data back and forth from the hard drive resulting in a big reduction in performance.

There are limits on how much memory your PC can use, it varies from one model to another, but the general advice is that recent PCs running Windows XP and everyday office and multimedia applications work best with at least 1 gigabyte of RAM (see also this weeks Top Tip). 

There are now at least a dozen different types of RAM memory module in use today and needless to say they are all incompatible with one another. Whilst it isn’t strictly necessary to know all of the terms and acronyms to upgrade your PC it is a good idea to commit a few of them to memory and this should help you to avoid buying the wrong type or being bamboozled by salespeople.

Older PCs used SIMMs (single in-line memory modules) and these had to be installed in pairs because of the way they handled data in 32-bit chunks. Virtually all of today’s memory modules are 64-bit DIMMs (dual in-line memory modules) and these can be installed singly, which makes memory upgrades in modern PCs a lot easier and cheaper. 

There are three different types of DIMM in widespread use and although they look similar they are not interchangeable. As well as being slightly different sizes the number of connecting pins varies and there are notches cut into the connector strips, which prevents them from being inserted into the wrong sockets or fitted the wrong way around.

All RAM memory modules are based on Dynamic RAM or DRAM technology. The oldest type still in widespread use is Synchronous DRAM (SDRAM). Modules operate on a 3.3-volt power supply and the main distinguishing feature is a 168-pin connector strip with two notches.

Currently the most popular type of memory and the sort you are most likely to have in your PC -- if it is less than 3 or 4 years old -- is Double Data Rate or DDR SDRAM. As the name implies it is more than twice as fast as SDRAM. DDR SDRAM modules use a 2.5-volt supply and modules have 184 connecting pins and a single notch.

The new kid on the block is DDR2 DRAM. Needless to say it is even faster than plain vanilla DDR; it also uses less power and is now making steady inroads into the PC market. The modules operate on a 1.8-volt supply and they have 240 pin connector strips with a single notch.

There’s one other type of memory module that’s worth a brief mention and that’s Rambus DRAM (RDRAM). This has been hovering around the fringes for a year or two and in spite of it being faster and even more efficient than rival memory technologies it hasn’t made much of an impact on the mainstream PC market, so far.

NEXT WEEK - Upgrading your PC’s memory, part 2

JARGON FILTER

FLASH MEMORY

Type of ‘non-volatile’ memory that retains data when the power is removed; widely used in digital cameras, media players and pen drives

MP3

Motion Picture Experts Group audio layer 3 -- digital audio compression system commonly used to send files containing audio and music over the Internet and for storing musical files in personal audio players

RAMBUS

US Corporation responsible for the development and promotion of a patented high-performance memory technology

TOP TIP

Another good reason to start thinking about upgrading your computer’s memory is Windows Vista, which is due to launch later this year. The official line is that the 32-bit version will operate with as little as 256Mb of RAM though the evidence so far from those who have tried it suggests that it needs a minimum of 512Mb to run, and ideally 1Gb or more for any sort of speed and stability. The more advanced 64-bit version will require at least 2Gb of RAM. Don’t forget there are hundreds of great Boot Camp Top Tips in the Archive.

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© R. Maybury 2006, 2501

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