And then there's the mysterious and often misunderstood processor clock speed, measured in megahertz, and now often in gigahertz.

FORBES: Silicon Confusion

Inside, the machine runs an Intel (nasdaq: INTC - news - people ) Pentium 4 processor with a clock speed of 1.7 gigahertz.

FORBES: Ten O'Clock Tech: Sony's Very-Video PC

Inside there's an Intel (nasdaq: INTC - news - people )-made Pentium 4 processor, the clock speed of which hasn't yet been revealed--though HP says it will be faster than 2 gigahertz.

FORBES: PCs Go Hollywood

As the initial wave of iPhone 5 reviews hit, it looked as if Apple's dual-core A6 processor was sporting a clock speed of around 1GHz.

ENGADGET: Apple's A6 CPU actually clocked at around 1.3GHz, per new Geekbench report

Things like the number of computer instructions per clock cycle, the bandwidth of the RAM bus, and the overall efficiency of the architecture are at least as important as the raw clock speed at which a processor runs.

FORBES: Nintendo Wii U Clock Speeds: Much Ado About Nothing?

Clock speed is only one factor affecting processor performance, but it's one that consumers pay close attention to.

CNN: Intel demos Pentium 4 at 2GHz

Clock speed is only one measure of processor performance, but it's one that PC buyers -- especially consumers -- tend to pay close attention to.

CNN: AMD's low-cost Duron chip takes aim at Celeron