How to buy the best new CPU

What not to buy
You'll still find some desktops powered by older processors, including the single-core Athlon 64, Celeron D, Pentium D, Pentium M, and even Pentium 4 processors. Though you might be tempted to snap up one of these bargain models, these processors typically run slower and hotter, and suck up more power than newer CPUs.

If you're using an older motherboard that doesn't support the newest processors and your budget accommodates only a new CPU, you may need to consider one of these processors. We'd suggest that you opt for newer designs, though.

At the other end of the spectrum, both Intel and AMD market processors specifically designed for use in file servers. Intel's Xeon and AMD's Opteron chips are typically at the leading edge of processor design, particularly when using multiple CPUs. Motherboards designed for these processors, however, typically require special registered, error-correcting memory, and are often designed to use more expensive SCSI hard drives. Plus, they usually don't support consumer-oriented performance technologies such as Scalable Link Interface (SLI) graphics, making server processors and motherboards a pricey option for desktop use.