Hardware Reference
In-Depth Information
Instead of buying “new” obsolete memory for older systems, check with computer repair
shops, Craigslist, websites specializing in surplus memory, or other users who might have a
collection of old parts.
High-reliability systems might want or need ECC versions, which have extra ECC bits. As with other
memory types, you can mix ECC and non-ECC types, but systems can't use the ECC capability.
Replacing Modules with Higher-Capacity Versions
If all the memory module slots on your motherboard are occupied, your best option is to remove an
existing bank of memory and replace it with higher-capacity modules.
However, just because higher-capacity modules are available to plug into your motherboard, don't
automatically assume the higher-capacity memory will work. Your system's chipset, BIOS, and OS
set limits on the capacity of the memory you can use. Check your system or motherboard
documentation to see which size modules work with it before purchasing the new RAM. You should
make sure you have the latest BIOS for your motherboard when installing new memory.
If your system supports dual- or triple-channel memory, you must use modules in matched pairs or
triples (depending on which type your system supports) and install them in the correct location on the
motherboard. Consult your motherboard manual for details.
Installing Memory Modules
When you install or remove memory, you are most likely to encounter the following problems:
• Electrostatic discharge
• Improperly seated modules
• Incorrect memory configuration settings in the BIOS Setup
To prevent electrostatic discharge (ESD) when you install sensitive memory chips or boards, you
shouldn't wear synthetic-fiber clothing or leather-soled shoes because these promote the generation
of static charges. Remove any static charge you are carrying by touching the system chassis before
you begin, or better yet, wear a good commercial grounding strap on your wrist. You can order one
from any electronics parts store. A grounding strap consists of a conductive wristband grounded at the
other end through a 1-meg ohm resistor by a wire clipped to the system chassis. Be sure the system
you are working on is unplugged.
Caution
Be sure to use a properly designed commercial grounding strap; do not make one yourself.
Commercial units have a 1-meg ohm resistor that serves as protection if you accidentally touch
live power. The resistor ensures that you do not become the path of least resistance to the
ground and therefore become electrocuted. An improperly designed strap can cause the power
to conduct through you to the ground, possibly killing you.
Follow this procedure to install memory on a typical desktop PC:
1.
Shut down the system and unplug it. As an alternative to unplugging it, you can turn off the
power supply using the on/off switch on the rear of some power supplies. Wait about 10
seconds for any remaining current to drain from the motherboard.
