Why are there limits on CPU speed?
When you buy a CPU chip, it has a “maximum” speed rating stamped on the chip’s case. For example, the chip might indicate that it is a 3-GHz part. This means that the chip will perform without error when executed at or below that speed within the chip’s normal temperature parameters. There are two things that limit a chip’s speed: • Transmission delays on the chip • Heat build-up on the chip Transmission delays occur in the wires that connect things together on a chip. The “wires” on a chip are incredibly small aluminum or copper strips etched onto the silicon. A chip is nothing more than a collection of transistors and wires that hook them together, and a transistor is nothing but an on/off switch. When a switch changes its state from on to off or off to on, it has to either charge up or drain the wire that connects the transistor to the next transistor down the line. Imagine that a transistor is currently “on.” The wire it is driving is filled with el
