Repairing and Upgrading Your PC

Other Memory Issues

In addition to memory type, speed, and timings, there are several other issues to consider in choosing proper memory for your system. We'll examine each of those issues in the following sections.

Dual-channel operation

For best performance, modern processors require a great deal of memory bandwidth—more than can be provided by a single memory module. For example, an Intel Pentium 4 processor with an 800 MHz FSB can use memory bandwidth up to 6.4 GB/s, twice that provided by a single PC3200 DIMM. To accommodate this need for greater bandwidth, chipset engineers designed dual-channel memory controllers that recognize two physical memory modules as one logical memory module, effectively doubling the data transfer rate between the CPU and memory.

WHEN DUAL-CHANNEL MEMORY MATTERS

Enabling dual-channel memory operation requires that the motherboard have a dual-channel memory controller and that you install memory modules in matched pairs. Ideally, the two memory modules should be identical, but most dual-channel motherboards will accept any pair of DIMMs as long as they are of the same capacity, type, and speed. Most dual-channel memory controllers will operate properly in single-channel mode if you install only one DIMM, but system performance may be significantly degraded.

Dual-channel operation may or may not be important to system performance, depending on the processor you use. For example, the fastest Athlon XP processors use a 400 MHz FSB. Because the Athlon XP ...