Back in the day, processor upgrades were fairly simple: find a faster processor in the same CPU family, flip a few motherboard configuration switches after installing the new processor, and you were ready to roll. Today, with processor families containing a bewildering array of options, selecting a processor upgrade is trickier than ever. Here's how to do it "by the numbers."
A processor upgrade involves a lot of numbers, but they can be divided into two categories:
Processor-related numbers include the socket number, processor model number, and processor specifications (clock speed, front side bus speed, L2 cache size).
Motherboard-related numbers include the motherboard model number (and brand), board revision number, and BIOS revision.
The Socket Number
The processor socket number is one of the most important factors in determining whether you can upgrade your processor, and what processors will fit, especially if you are planning to upgrade an AMD-based system. Most Intel processors in recent years have used Socket 775, but 64-bit AMD processors have used Socket 754, Socket 939, Socket 940, Socket AM2, and Socket AM2 Plus. A processor upgrade must fit into the same socket as your existing processor.
The Processor Model Number
Although older Intel Pentium 4 processors don't use model numbers, most recent Intel processors are identified by model numbers. Model numbers are used primarily as a way to compare relative performance and features in a particular processor family, such as the Intel Core2Duo or AMD Athlon 64 FX families: higher numbers might mean higher clock speeds or other additional features.
Once you know the processor model number, you can look it up to determine the exact features it supports, so you can choose an upgrade that is faster and may support additional features.
Processor specifications refer to numbers such as clock speed, L2 cache size, L3 cache size, clock speed, number of processor cores, and front side bus speed. If you are looking for an upgrade processor from the same family as your current processor, the upgrade should have a faster clock speed, the same or larger L2 cache size, and the same or faster front side bus speed.
If you switch processor families, though, comparisons can be trickier.
The slowest Intel processors are those in the Celeron D family. The Pentium 4 and dual-core Pentium D processors, despite their high clock speeds, actually perform real-world tasks more slowly than the Core2Duo. The Core2Quad is the fastest Intel desktop processor family.
The slowest 64-bit AMD processors are those in the Sempron family. Keep in mind that Sempron was also used to identify some 32-bit AMD processors as well. The Athlon 64 and 64 x2 (dual-core Athlon 64) occupy the mid-range, and the Athlon 64 FX (available in single and dual-core versions) occupies the high end.
Note that most of the fastest processors feature two or more processor cores. A multi-core processor is essential for heavy multitasking without slowdowns and for optimized use of multithreaded applications.
Although most recent Intel processors use Socket 775, differences in support for dual and multicore processors can prevent some Socket 775 motherboards from accepting certain processor models or families. And, whether you use Intel or AMD processors, limitations in voltage support or BIOS issues can also limit your processor upgrade options.
To make sure you know the processor upgrade options for your system, you must know the motherboard brand, model number, motherboard revision, BIOS revision, and chipset model number.
The chipset model number, although it's listed last, may be the most important of all motherboard-related numbers, as it determines the processor models that can be used on a particular motherboard and the motherboard's major features.
Finding Out What's Under the Hood
As you can see from this discussion, knowing exactly what processor and motherboard you are currently using is essential to choosing a processor upgrade. If you have a well-documented "white box" system, you may already know exactly what processor model and motherboard model is inside your system. But if you don't, a number of useful – and free – programs can be used to Xray your system. Some of my favorites include:
In the next part of this tip, I'll help you use the information you discover to choose the best processor upgrade for your needs.