Ultimate Memory Guide
Ultimate Memory Guide
WHAT TO CONSIDER WHEN BUYING MEMORY
One of the quickest and easiest ways to identify the right memory modules and expansion options for
your computer is to use a memory configurator. Like some of the other major memory manufacturers,
Crucial makes a memory configurator available. You can access Crucial 's configurator
through our home page at www.flexxmemory.co.uk . The most important thing to ensure when buying memory is compatibility with your system.
In addition, you'll need to decide how much memory you need and beyond that lie considerations
of price, quality, availability, service, and warranty. This section helps you address these important
decision factors and helps you answer questions like these:
* How much memory do I need?
* How much memory will my system recognize?
* What kind of memory is compatible with my system?
* How many sockets are open and how should I fill them?
* How do I determine the quality of memory?
* What should I know about memory prices?
* What other issues should I consider?
As mentioned earlier, compatibility of memory components with your computer system is arguably
the most important factor to consider when upgrading memory. This section can get you started;
it also makes frequent mention of the advantages of using a memory configurator.
WHAT KIND OF MEMORY IS COMPATIBLE WITH MY SYSTEM?
The easiest way to determine what type of memory goes with your system is to consult with your
system documentation. If you need further assistance, consult a memory configurator available from
many sources, including Crucial
such a tool to help you find the right memory configuration for your system.
With Crucial configurator, you can search by five different criteria:
* System manufacturer/model
* Computer model name
* Memory module part number (Kingston, distributor, manufacturer)
* Generic memory
WHAT IF I CAN'T FIND MY SYSTEM IN A MEMORY CONFIGURATOR?
If you can't find your system in the memory configuration programs, you can still find out what
kind of memory you need by consulting the manual that came with your system. In most cases,
the manual will provide basic specifications such as the speed and technology of the memory you need.
This information is usually enough to choose a module by specification.
If you don't feel you have enough information, you can call your system manufacturer,
or email us on firstname.lastname@example.org free technical support and assistance.
HOW MANY SOCKETS DO I HAVE OPEN?
You may or may not have an idea what the inside of your computer looks like and how memory is configured.
You may have opened up your computer when you bought it to see the configuration inside, or you may have
looked at a configuration diagram in your user's manual. Even if you have no idea of the memory configuration of
your system, you can use Kingston's memory configuration tools to find out. For each system, the
configuration includes a diagram, called a bank schema, which indicates how the memory
sockets are arranged in your system and what the basic configuration rules are.
The simple tutorial on the next page outlines how to use a bank schema diagram to
determine the number of sockets in your system and how to fill them.
HOW TO READ A BANK SCHEMA
A bank schema is a diagram of rows and columns that shows the number of memory sockets in your system.
This diagram is a theoretical bank layout and not an actual system board layout; it is designed to help you quickly determine configuration requirements when adding memory modules.
In a bank schema, each [__] represents a memory socket:
Example: [__][__][__][__] = 4 memory sockets
Each column in the diagram represents a memory bank. The number of "[__]" symbols in a column
represents the number of memory sockets in a bank. Upgrading is performed one bank at a time.
For example, if there are four columns with two [__] in each column, upgrading is done two
modules at a time. However, if there is just a single row of [__], upgrading may be performed one module at a time.
8 sockets = [__][__][__][__][__][__][__][__] (Modules may be installed one at a time in any combination)
8 sockets (4 banks of 2) = (Modules must be installed two at a time)
4 sockets (1 bank of 4) = (Modules must be installed four at a time)
The standard memory (base amount that the system was shipped with) appears in the diagram as
either removable or non-removable.
Removable memory comes in the form of modules that fit into memory sockets, and, if desired,
can be removed and replaced with modules of higher capacity. Removable memory is represented
by a "" symbol with a number next to it: 4 [___] indicates that a 4MB module is in the first
socket and that the second socket is empty.
Non-removable memory usually comes in the form of memory chips soldered directly onto the system board.
It is represented in the bank schema in brackets: [_4MB_] indicates 4MB of non-removable memory
soldered onto the board and two available memory sockets.
If your system is not included in the configurator, you may be able to find out how many sockets are in the
system and how many are filled by pressing the F1 key during system startup.
If your system supports this, a screen will appear that indicates how many memory sockets are in the system,
which ones are filled and which are open, and what capacity modules are in each socket.
If pressing the F1 key during startup doesn't produce this result, check your computer's system manual for more information.
As a last resort, you can open your computer and take a look at the sockets.
(Important Note: Before removing the cover of your computer, refer to the computer's system manual
and warranty information for instructions and other relevant information.) If you do open the computer,
you may be able to identify "bank labels" that indicate whether memory are installed in pairs.
Bank numbering typically begins with 0 instead of 1. So, if you have two banks,
the first bank will be labeled "bank 0", and the second bank will be labeled "bank 1."
HOW SHOULD I FILL THE SOCKETS?
In most cases, it's best to plan your memory upgrade so you won't have to remove and discard the memory
that came with the computer. The best way to manage this is to consider the memory configuration
when you first buy the computer. Because lower-capacity modules are less expensive and more readily available,
system manufacturers may achieve a base configuration by filling more sockets with lower-capacity modules.
By way of illustration, consider this scenario: a computer system with 64MB standard memory comes with
either two (2) 32MB modules or one (1) 64MB module. In this case, the second configuration is the better
choice because it leaves more room for growth and reduces the chance that you'll have to remove and
discard lower-capacity modules later. Unless you insist on the (1) 64MB module configuration,
you may find yourself with only one socket left open for upgrading later.
Once you have purchased a computer and are planning your first upgrade, plan to buy the highest-capacity module
you think you may need, especially if you only have one or two sockets available for upgrading.
Keep in mind that, in general, minimum memory requirements for software applications double
every 12 to 18 months, so a memory configuration that's considered large today will seem much less so a year from now.
As with any type of product, memory can vary in the quality from one manufacturer to another. In general,
the larger, more established brand name companies are more consistent in adhering to tight design specifications,
using high-quality components, and establishing certified quality control processes for manufacturing and thorough testing.
That's not to say that lower-quality modules don't work fine - they may be the right solution,
depending on how hard you work your system. In deciding the level of quality you require, consider the following:
1. If the memory you buy doesn't perform well, will you be comfortable returning it for a replacement?
Would you have the time to deal with removing the memory and waiting a couple of days to a week to get the situation resolved?
2. When memory is of low quality, you often experience intermittent problems, such as the computer
"freezing" unexpectedly, or having frequent errors. How often do you save your work, and if you were
to lose your work, how much would that cost you? If you use your computer to play games, read email,
and surf the Internet, such interruptions and losses may not be a big problem. But if you're running a business,
losing a few hours of work could be a serious matter.
3. The biggest risk with unreliable memory is data corruption: that is, some bits of data may change or be read incorrectly.
The result of data corruption could be as harmless as a syntax error in a document, or as potentially serious as a
miscalculation in a spreadsheet. How important is the accuracy of the work you do on your computer?
Again, if you use your computer for gaming, writing letters, and the Internet, it may not be a problem.
But if you're managing your finances, you may want to do all you can to assure the reliability of your data.
4. Just like all products, the quality and durability you require depends on how you use it. Computer applications
that require a lot of memory usually work the memory very hard. These applications often work better with memory
that exceeds the system's speed and reliability specifications. If you're working in multimedia or using heavy
number-crunching programs, the chance of a lower-quality memory module failing is greater than if you're
only doing light work, such as simple word processing.
ASSESSING MEMORY QUALITY
Here are some important factors to keep in mind when assessing the quality of a brand of memory:
Designers of memory modules can follow strict specifications or take short cuts to save money on components.
In general, manufacturers who do in-house design have more control over the quality of the module than those who farm this work out.
The quality of the DRAM chips, PC boards, and other components used on the module are critical
to the overall quality of the module. Premium memory chips can cost up to 30% more than low-grade chips and
high-quality PC boards cost about 50% more than lower quality alternatives.
Many factors in module assembly can affect the overall quality of the module. In addition to proper handling of components,
solder quality affects how reliably information can travel from the chip to the module and back.
The temperature and humidity in the assembly and storage areas must be regulated to prevent warping,
expansion, and contraction of components during assembly.
Electro-Static Discharge (ESD) is one of the most common causes of damage to a memory module.
ESD damage can result from excessive and inappropriate handling. Memory modules should only be
handled by workers who are properly "grounded" and modules should be properly packaged to protect against ESD during shipping.
The more thoroughly memory has been tested before it is shipped, the less chance of problems during
operation. In addition to standard production tests to ensure that the modules have been built correctly,
memory can be tested for compatibility in the systems in which it will be used. The DRAM core can be tested
for chip reliability, and modules can be tested "at speed" to make sure they will work in high-use situations.
Some companies perform testing at all levels, and some do less testing.
PRICING AND AVAILABILITY
This section contains information that helps make sense of the fluctuations that can occur in the memory market.
THE DRAM CHIP MARKET
Memory modules are made with DRAM chips, which are manufactured in mass quantities in enormous fabrication
plants (often referred to as "fabs"). Fabs can take up to two years to build and require substantial capital investment:
approximately $3 billion per plant. These time and cost factors directly affect on the ability of the memory market to
adjust quickly to fluctuations in supply and demand. When demand for memory chips increases, chip manufacturers
typically do not respond immediately because the investment required to add more capacity is substantial and may not pay off,
especially if all the competitors are doing so at the same time. Therefore, the immediate effect is that prices rise as manufacturers
assess whether the increase on demand is temporary or substantial enough to warrant investment. By the same token,
when there is an oversupply situation in the market, chip manufacturers are willing to sustain losses for a long time while
prices fall to below breakeven levels. This is because in many cases it costs more money to shut a plant down than to continue
to produce and sell chips at below cost. Also, the longer a manufacturer can hold on, the greater
the chance of "being there" to reap the rewards when competitors reduce capacity and the market turns around again.
WHY MEMORY PRICES FLUCTUATE
There are several factors that can affect memory prices. A few of these include: demand, DRAM manufacturing levels,
inventory in the marketplace, time of the year, new operating system releases, and computer sales.
All these things can affect memory prices at different times, either separately or simultaneously.
The most important thing to keep in mind when buying memory is that the price of 256MB today will most
likely be different than the price of 256MB next quarter. The best rule of thumb is to compare memory prices
close to your time of purchase. When doing price comparisons, it's more important to make sure you are making
equivalent comparisons on module types than how the actual price per MB varies over time. If there are shortages
in the market it's most important to be sure that what appears to be a "great deal" isn't a "short-cut" module built
from off-spec components. In an oversupply market, you're much more likely to get a great price, but keep in mind
that many manufacturers are losing money and may take shortcuts on testing and other expensive production quality
measures to compensate. Refer to the quality section above for more details on this.
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