Hardware Reference
In-Depth Information
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 have access to 3.5GiB. However, on a newer
system with two or more PCIe x16 slots, and especially with two or more high-end PCI Express
video cards installed, you may drop the usable limit to something close to 2GiB.
When running 32-bit editions of Windows, I used to recommend installing a maximum of 3GB RAM,
because most if not all of the fourth GB is unusable. However, on systems that support dual-channel
memory, it is usually cheaper to install two 2GB modules to get 4GB than it is to install two 1GB
modules and two 512MB to get 3GB. On desktop systems that support dual-channel memory, you
would not want to install three 1GB modules because in that case not all the memory would run in
dual-channel mode.
