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Doubling up
Games consoles were predicted to sound the death knell for the home PC. It never happened. Sub-1000 notebooks with genuine gaming power however, now that's a different kettle of kippers. While games consoles can lack the ability of a keyboard and mouse coupled to a high resolution screen, notebooks have more. Being able to tuck it under your arm to sit outside in summer or slipping it into a bag to use on that long train journey has a very definite appeal.

It's not unusual to find me poking around local PC retailers checking out prices and generally just being nosey, but on this particular occasion I had a motive. I was scouting for a new notebook and a certain high street retailer seemed to have an unusually good range at unexpectedly keen prices.

There were four models on my short-list, all at under 600 and yet at a specification good enough to be classified as midrange rather than entry level. At the end any of the final four would have served me well and it was purely down to minor specification and design differences that prompted me to choose an ACER Aspire 1691.

As I pondered my final decision, one of the factors I took into consideration was memory, and it dawned on me that several of the notebooks I'd looked at were guilty of having their memory implemented by means of just a single module. Not much of a crime you'd think, but all these notebooks featured Intel chipsets that supported dual channel memory.

For those of you not familiar with the principles of dual channel memory let me explain. Imagine your memory as being like the check-out at your local supermarket. People (data) queue up to be dealt with, and the faster the cashier the faster the queue moves. Dual channel memory basically opens up an extra checkout alongside the first, and two checkouts means considerably faster processing, right? Well yes it does, but only if you've got two cashiers. The point is placing just a single memory module in a dual-channel capable motherboard is akin to opening two checkouts and placing a cashier on just one of them.

So why equip a notebook with the capability to run dual channel memory then cripple it by installing just a single piece of memory? The manufacturers don't seem to have an answer which means it's either a ploy to get you on the phone ordering more memory, or they just whip a module out of a similar machine which normally comes with 1GB of memory. Another possibility is that they just don't consider it at design. It is true that offering 512Mb in one module, as they did in my case is better than offering 256Mb in two modules when coming to upgrading. This means I don't have to throw away both modules should I want 1GB of memory.

This seemed like the perfect opportunity to demonstrate the benefits of adding an extra stick of memory and, in one fell swoop, enabling the performance benefits of running in dual-channel mode.

The route we've taken in this particular article is slightly unrealistic in that most of you owning a laptop with a single 512MB module would be advised to simply purchase a second one, thus doubling your memory capacity and by default enabling dual channel. Rather than do this it was decided we should replace the existing 512MB module with a pair of 256MB modules. This enables dual channel memory access but, by keeping the capacity the same gives an accurate representation of the performance increases available purely from switching from single to dual channel mode.

Before you can order more memory you do, of course, need to know what type of memory you need. There are several ways to do this. There are several retailers that help you find the correct memory for your system, alternatively you can download a free diagnostic program such as EVEREST Home Edition which will tell you what you've got installed.

Once my modules arrived (Ours were supplied by Crucial), it was time to see what difference they made.