Memory FAQ
How
can I "max out" the memory on my
computer?
You can determine the largest memory
module each slot can take by
dividing the maximum capacity by the
total number of slots. For example,
if your computer has a maximum
memory capacity of 512MB and has two
slots, the largest module you can
install in each slot is a 256MB
memory module.
However, there are exceptions to
this general rule. For example,
there are situations where a
computer with 4 memory slots and a
2GB maximum memory capacity will
accept two 1GB modules. There are
also times when a system would only
accept a 512MB module at launch, but
down the road would take a 1GB
module with a BIOS upgrade.
To completely "max out" the memory
on your computer, you may need to
actually remove memory modules
currently installed and replace them
with larger-capacity modules. Using
the example above, if your computer
has one 512MB module already
installed, with one memory slot
open, you would need to remove the
512MB and install two 1GB modules to
truly "max out" your computer.
Do I
have to buy the same size upgrade as the
memory module currently installed in my
computer or can I mix different sizes?
In newer systems using SDRAM or DDR
SDRAM memory, you can use modules of
different densities with no problem. For
example, if your computer came with a
128MB memory module, you can add a 256MB
module for a total of 384MB of RAM.
However, if you have a "dual-channel"
system and want to take advantage of
that technology, you will need to ensure
that the modules in each memory slot are
the same density.
ECC vs.
non-ECC — What do I Have and Can I Mix?
When adding new memory, you should match
what is already in your system. Adding
non-ECC memory to an ECC system will
disable the error-checking and
correcting ability of your memory
modules. While your system may still
operate, the enhanced features of the
ECC modules will no longer be active in
you computer.
You can determine if your system has ECC
by simply counting the number of black
memory chips on each module. ECC (and
parity) memory modules have a chip count
divisible by three or five. This extra
chip detects if the data was correctly
read or written by the memory module. If
the data wasn't properly written, the
extra chip will correct it in many cases
(depending on the type of error).
Non-ECC (also called non-parity) modules
do not have this error-detecting
feature. Any chip count not divisible by
three or five indicates a non-parity
memory module.
Using ECC decreases your computer's
performance by about 2 percent. Current
technology DRAM is very stable, and
memory errors are rare, so unless you
have a need for ECC, you are better
served with non-parity (non-ECC) memory.
What are
the benefits of upgrading your computers
memory?
Upgrading your memory is typically the
easiest and least expensive way to
upgrade your computer for a significant
boost in performance. The computer's RAM
memory is its workspace, or where all of
the instructions it needs to act on are
stored temporarily. Think of the RAM as
the desk you use to sort through your
work. If the size of that desk is small,
your efficiency is limited in comparison
to a larger desk that allows you to work
more effectively and efficiently.
Similarly, a computer with more RAM can
work more efficiently because it does
not need to retrieve information from
the hard disk drive as often. A memory
upgrade is particularly helpful for
users who work with large files, have
more than one program open at one time,
or use memory-intensive applications
such as games or graphics and video
editing software.
How do
you know it's time for a memory upgrade?
There are several signs indicating it
may be time to upgrade your memory. If
you see your mouse pointer turn into an
hourglass for significant periods of
time, if you hear your hard drive
working, or if your computer seems to
work more slowly than you expect, the
reason is probably insufficient memory.
When physical memory is insufficient,
the system uses Hard Disk Space as
memory. This is called "Virtual Memory".
Since access time of Physical memory is
in tens of NanoSeconds and Access time
of Hard Disk is in MilliSeconds, the
system slows down considerably.
.What's
the difference between buffered and
unbuffered DIMMs?
High density DIMMs have lots of chips on
them and therefore possess a higher
capacitive load on the address and
control signals in comparison to lower
density DIMMs. Some designers use
redrive buffers on the DIMM to boost the
signals to reduce system loading when
compared to the same high density module
without buffers. But the buffers
introduce a small delay into the
electrical signal, so adding buffers to
a standard density module would have the
effect of slowing down the signal,
compared to the same low density module
without buffers.
What is
Virtual Memory?
This is a method of extending the
available physical memory on a computer.
In a virtual memory system, the
operating system creates a pagefile, or
swapfile, and divides memory into units
called pages. Recently referenced pages
are located in physical memory, or RAM.
If a page of memory is not referenced
for a while, it is written to the
pagefile. This is called "swapping" or
"paging out" memory. If that piece of
memory is then later referenced by a
program, the operating system reads the
memory page back from the pagefile into
physical memory, also called "swapping"
or "paging in" memory. The total amount
of memory that is available to programs
is the amount of physical memory in the
computer in addition to the size of the
pagefile.
Will
adding more RAM make my Internet
browsing faster?
Maybe. Internet browsing speed depends
on a huge number of factors, including
your connection speed, traffic on the
site you're visiting, and the other
components in your system. You will
probably notice the biggest improvement
from additional RAM if are viewing or
working with large files (such as photos
and digital audio and video) or if you
switch between your browser and other
applications often.
What's
the difference between RDRAM and SDRAM?
RDRAM stands for Rambus Dynamic Random
Access Memory. SDRAM stands for
Synchronous Dynamic Random Access
Memory. The two memories are completely
different memory technologies and are
not compatible with each other. RDRAM is
a unique design developed by a company
called Rambus, Inc. RDRAM is extremely
fast and uses a narrow, high-bandwidth
"channel" to transmit data at speeds
much faster than SDRAM. |
