PC Hardware in a Nutshell, 3rd Edition

Multiple CPU support

Some chipsets support motherboard configurations with multiple CPU sockets. These chipsets coordinate operations between the multiple processors and memory, which is necessary but not sufficient to allow symmetric multiprocessing (SMP) operation. In addition to chipset support, SMP requires:

CPU SMP support

Non-Intel CPUs other than the AMD Athlon and Duron lack the circuitry to support SMP. Intel fifth- and sixth-generation CPUs support SMP, except Coppermine128-core or later Celerons and most Coppermine-core Pentium IIIs at 1 GHz and faster. The Pentium 4 does not support SMP except in its more expensive Xeon variant. AMD produces a special version of the Athlon called the Athlon MP that supports SMP applications in conjunction with the AMD-760MP or AMD-760MPX chipset.

Operating system SMP support

DOS, Windows 3.X, and Windows 9X do not support SMP. Running one of these operating systems on an SMP PC uses only one of the CPUs. Windows NT/2000/XP Pro supports SMP, as do most Intel-based Unix implementations, including Linux. Note that Windows XP Home does not support SMP.

If you run an SMP-aware operating system, consider buying a motherboard that supports dual CPUs. The incremental cost is generally small, and the increased performance is significant. Prior to 2001, Intel’s pricing strategy often made buying two midrange Pentium III processors less expensive than buying one top-of-the-line Pentium III. Although the AMD Athlon and Duron processors were inherently ...