Hardware Reference
In-Depth Information
Can any of that unused memory between 3GB and 4GB be reclaimed? For those running
a 32-bit OS, the answer is no. However, if you are running a 64-bit OS on a system that
supports memory remapping (primarily a function of the motherboard chipset and BIOS),
the answer is yes. Most newer motherboard chipsets have a feature that can remap the
otherwise disabled RAM in the fourth gigabyte to the fifth (or higher) gigabyte, where it
will be both visible to and usable by a 64-bit OS. Note, however, that if the motherboard
doesn't support remapping, even when a 64-bit OS is being run, the memory will be lost.
Notethatthe3GBlimitisnotasstrictlydefinedasitwaswiththe640Klimit.Thismeans
that if you do install 4GB, you might get to use as much as 3.5GB of it, or possibly as
little as 2.5GB or less. It depends largely on the types of buses in the system as well as
the type and number of video cards installed. With a single low-end video card, you may
