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SODIMM Memory FrequencySODIMM Memory CapacitySODIMM Memory TimingsConclusion

SODIMM Memory frequency, capacity, timings - how to balance your upgrade

Your laptop grinds under the strain of software memory requirements forcing you to purchase a laptop memory upgrade. The question is, how do you go about buying an upgrade that reaps the most benefits? Weíll take a look at this below.

SODIMM Memory Frequency

Regardless of the type of memory, be it SDRAM, DDR, DDR2, DDR3 etc. memory frequency pays a pivotal role in its performance. You see, frequency influences the speed at which bytes can be read and written to and from a SODIMM memory module.

The faster the frequency of a SODIMM memory module, the greater the bandwidth available to your system, thus ultimately the software you run. Some software benefits more than others when more bandwidth is available, nevertheless itís generally a good idea to have more of it if possible.

Of course depending on your model of laptop, it might not be possible to make use of higher frequency SODIMM memory modules. The underpinning for this is simple, while a laptop supporting for example PC2-4200 DDR2 SODIMM memory that runs at 533MHz effective can have a higher rated SODIMM memory module of the same type but higher grade installed (i.e. PC2-5300 DDR2 running at 667MHz), the net result will still be memory that runs at a maximum of 533MHz. This is true unless of course the memory controller in that laptop supports the frequency of the faster memory. Normally laptop manufacturers already install the fastest grade of memory during production..

Should you conclude that your laptop does support faster SODIMM memory modules, it may just be worth upgrading all the installed memory to whatever highest grade is supported. Memory frequency is the number one contributor to memory bandwidth therefore by in large performance. Do note how we wrote ďallĒ the installed memory. You see, for your laptop to run at the faster memory frequency, all installed SODIMM memory must meet this specification thus be of the same grade. If your laptop has two SODIMM memory slots (this is the norm) then in practise both SODIMM memory modules must be identical. For example, in a DDR2 memory based laptop this might be PC2-6400, in a DDR laptop PC3200, in a SDRAM laptop PC133 or any other available combination. Simply follow this line of thought and youíll be okay.

Read up on SODIMM memory frequency and characteristics.

SODIMM Memory Capacity

The amount of memory you have installed in your laptop is what generally speaking ultimately defines how smooth software runs. Consequently, while memory frequency is a key factor to SODIMM memory performance, the capacity of memory installed is fundamental for overall system performance.

How much memory you need is dependant on what software you run. Unfortunately, thereís no golden rule that magically works for each and every application out there. Fortunately however thereís an old principle that lends a helping hand: more memory always helps. Essentially what this translates to in practise is this: install more memory than you need as this way youíre far less likely to run into slowdowns, providing of course the slowdowns are the result of low system memory and not, per se, the processor, graphics card, storage device etc.

Does this sound too good to be true? Regrettably yes, for three reasons. Firstly, buying too much laptop memory will likely aid laptop performance at the cost of upsetting your wallet. Secondly, in an ideal world all laptops, be them new or old, would support the currently maximum capacity of available SODIMM memory modules. Obviously the world isnít an ideal place and thus you can only upgrade to the maximum capacity supported by your laptopís memory controller. Thirdly, if youíre running a 32bit Operating System on a laptop supporting 4GB or more of memory then just keep in mind that even though the memory will work, applications will not use the full 4GB. This is a limitation of 32bit addressing, only some of this namespace is available to system memory, the rest must be used for addressing other types of memory within your laptop, for example that of the graphics card. To overcome this on laptops that support it, upgrade to a 64bit Operating System.

Starting to sound slightly complicated? Letís break this down into simple English. What you should deduct from this is as follows: buy as much memory as your wallet and laptop allows but consider the limitations of 32bit Operating Systems. If you plan to upgrade to 4GB or more of memory and have a newer laptop then upgrade its Operating System to a 64bit version. If your laptop supports 4GB but only 32bit Operating Systems then just keep in mind that the maximum your applications will likely see visible thus use is around 3.25-3.5GB.

Find out more about SODIMM memory capacity and guidelines.

SODIMM Memory Timings

Computer memory feature whatís known as timings. These are numerical values which represent delays in how a SODIMM memory module operates. The actual values vary depending on the type of memory (i.e. DDR2) and whether the given SODIMM memory module is mainstream or a performance part. Such delays control all the types of commands that get executed when your computer issues a read, write or copy command. Such timings are stored on each SODIMM memory module in whatís known as a SPD (Serial Presence Detect) chip, located on the same PCB (Printed Circuit Board) as the memory chips.

Because memory timings are ultimately delays then one might think itís logical to assume that lower timings are better. This can be answered as true but only to an extent. You see, there is only so much that these timings can be lowered, even if a SODIMM memory module has been binned as a performance part. This is due to synchronisation issues. Memory timings control how slow or how fast a given operation is processed by a SODIMM memory module. If itís set too fast then the outcome may be unstable operation. At the very least this will cause erroneous software behaviour, or if youíre less fortunate a system halt.

Since enhanced memory timings can only contribute so much to real-world system performance (circa 5% real-world performance boost), itís really a case of deciding whether you believe the added speed boost (i.e. slightly more memory bandwidth, somewhat lower memory access latency) is enough to warrant the price premium. Various tests over the years suggest no, even if you install ďperformanceĒ SODIMM memory, youíre not likely to feel the difference in any type of software but benchmarks.

Learn more about SODIMM memory timings and characteristics.


There are some important facts to recall from the above. First and foremost memory frequency plays a pivotal role in memory performance, otherwise defined at the speed at which memory read, write and thus copy commands get processed. The higher the memory bandwidth, the more it indirectly influences overall system performance. Secondly, memory capacity is what directly affects the overall speed of your laptop by having a direct influence on computer performance. The more memory you have installed, the far less likely you are to run into slowdowns caused by insufficient memory resources available to the Operating System and other software. Thirdly, memory timings act as an icing on the cake (for a better term) to both memory frequency and capacity.

The above is the theory, but what should you do when getting ready to buy your laptop memory upgrade? Always get the highest frequency of SODIMM memory your laptop supports by determining the highest speed grade supported by its memory controller. Wherever your wallet permits, also try and upgrade to a healthy amount of memory, above what youíre bound to currently use thus leaving yourself some headroom. Do however remember that your laptopís memory controller also limits the maximum capacity you can upgrade to. Finally, where feasible (something you will have to deduce yourself), choose a SODIMM memory module(s) with faster (lower) timings - if performance parts arenít available then the most you will lose is about 5% overall system performance.

Would you be interested in viewing other general laptop memory articles? If so simply click the button below and choose your desired topic by clicking its title.

Read the Laptop Memory Upgrades Guide to learn about all the aspects you should know when buying laptop memory...

...alternatively discover Where to buy 100% compatible SDRAM, DDR, DDR2 and DDR3 SODIMM memory.

PC2-6400 800MHz DDR2 200-pin SODIMM Dual Channel kits

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