user manual

AN806: Memory Upgrade Resource Guide Page 4
for the video memory. As another example, if we were to add a sound card with 64mb of
onboard memory, the addressable amount of system memory would drop to approximately
3.186MB.
In the configuration above, I have approximately 768MB of system memory that cannot be
addressed by the OS. Therefore, it cannot be utilized. However, the positive is that I do
have 3.25GB of usable system memory. This is a substantial increase over 2GB so a
person should not consider this address space limitation as a reason not to upgrade to 4GB
of system memory. Also, 4GB is good advantage at a later date should the user upgrade to
a 64bit OS.
For users wanting to fully utilize 4GB or more of system memory, a 64bit OS is required.
How Does This Apply to My Laptop?
The same basic rules apply for upgrading the memory in a laptop. In fact, most laptops
typically have a slower hard drive speed than the average desktop; 5400rpm for laptops
versus 7200 for desktops. So, if you have constant heavy page file usage on your laptop,
this can cause a level of input/output activity, called thrashing. Thrashing greatly reduces
performance. Hard drive thrashing can cause stutter in video playback, game or application
lag, slow page loads, and many other undesirable effects. A memory upgrade is one of the
most effective laptop upgrades.
Laptops have 2 memory slots due to size and space restrictions. And, the same rule of
adding matched modules should be applied which means the user will have the original
memory left over after the upgrade. Regardless, the performance benefits are worth it as
much if not more than with a desktop.
Corsair laptop memory is offered in 1GB (single SODIMM), 2GB (2 x 1GB SODIMMs) and
4GB (2 x 2GB SODIMMs) kits. So, users should also keep the 64bit OS option in mind
when selecting the 4GB kits. However, even those users selecting 4GB with a 32bit OS will
benefit from the increased memory just like a desktop user.
Notebook Memory Kits: http://www.corsairmemory.com/products/notebook_home.aspx
Summary
Users that are building new machines or users considering upgrading existing machines
with more memory have many things to consider before making a memory purchase. The
choice of the operating system is essential and will apply at both stock and overclocked
settings. The number of modules has an impact on the performance of the memory
controller that is independent of the operating system and must be accounted for. And,
users that choose to overclock must make a careful assessment of both how much memory
they want and how fast they want to attempt to run their memory. And, the motherboard