- What is a CPU?
- Tracing an instruction
- L1/L2/L3 Cache
- Clock cycle speed
- Front side bus (FSB)
- The numbers game: Intel vs AMD
- Sockets and slots
- Dual-core and quad-core CPUs
- 64-bit processors
- Mobile Processors
- Budget lines: Celeron, Sempron and Athlon
Sockets and Slots
The packaging that CPUs come in has evolved over time, as have approaches to how the CPUs 'slot' into the motherboard. The socket type on your motherboard of choice pretty much determines the processor that can run on it -- you can't fit an AMD chip on a motherboard designed for an Intel chip. Chipsets and processors are inextricably linked, and the practical upshot of this is that if you're in the market for a new CPU, unless it shares a very recent history with existing processor models, you'll probably be in the market for a new motherboard and supporting chipset as well.
You may also need to consider purchasing new memory, as that's also a factor that changes over time. With the move towards high speed DDR3 memory on some Intel-based motherboards, you might not be able to take the 1GB of memory from your old system and install it in your new one; DDR3 slots are physically incompatible with DDR2 slots. At the time of writing, only a few motherboards on the market featured DDR3 slots. Some motherboards do have DDR2 and DDR3 slots, so either or memory technology can be used.
Intel sets the pace for its processor chipsets, and does manufacture motherboards as well, although a number of third-party manufacturers (such as ASUS, Abit, Gigabyte and MSI) also licence the chipsets to use on motherboards. The onboard chipset also works in combination with the CPU to run certain CPU-specific tasks. Buying a motherboard with the latest chipset is recommended, as it will give you the best features and performance for the widest range of CPUs. But, if you're on a budget, you may be able to buy a motherboard that uses a slightly older chipset. Be sure that the motherboard you want to buy has a chipset that will support your CPU.
Intel's current desktop processor lines use the pinless (land grid array) LGA775 package, so motherboards with an LGA775 CPU socket is required. Older Pentium 4 CPUs used a 478-pin socket design. On the AMD side of the fence, Socket AM2 packaging is prominent and Socket 939 has been phased out. Earlier models used Socket 754 configurations. Another socket that is used for high-end Athlon CPUs is the early Athlon 64 FX CPUs which used a 940-pin CPU socket and a chipset that required more expensive registered memory. Some of the latest Athlon 64 FX CPUs use an LGA package called Socket F, which is a pinless design, and is primarily used for AMD's Opteron CPUs. Opteron is a CPU for high-end workstatioins and servers, rather than desktop PCs. Motherboards for these CPUs can use regular or registered memory. Both Intel and AMD provide Web resources to help you identify the correct matching chipset for each of their processors, and any decent vendor should be able to do likewise. (Intel: http://indigo.intel.com/mbsg/ AMD: http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_869,00.html).