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Speeding Up Processor Operations Overview

You can determine the speed of a processor by looking at the model number on the chip, but processors frequently have devices attached to them for cooling, which makes it difficult to see the writing on the chip. A processor commonly does not use its maximum speed all the time in order to save power or stay cool. Also, a processor is not always functioning at its maximum potential for a lot of reasons including coding used within an application, the user switching from application to application, inadequate bus width, or the amount of RAM installed. The processor can also operate beyond its rated specifications. Intel Turbo Boost allows the processor to operate faster than it is rated in order to handle periods of increased workload.

We have already taken a look at how increasing the CPU pipeline can, to some extent, improve processor operations, but other technologies also exist. We will start by defining some of the terms that relate to this area and associating those terms with concepts and the various technologies used. Table 3.1 list some terms related to speed.

TABLE 3.1 Motherboard speed terms



clock or clock speed

The speed of the processor’s internal clock, measured in gigahertz.

bus speed

The speed at which data is delivered when a particular bus on the motherboard is being used.

front side bus (FSB)

The speed between the CPU and some of the motherboard components. This is what most people would term the motherboard speed. Sometimes the speed is listed in megatransfers per second, or MT/s. With MT/s, not only is the speed of the FSB considered, but also how many processor transfers occur each clock cycle. A 266MHz FSB that can do four transfers per second could list as 1064MT/s. The FSB is being upgraded with technologies such as AMD’s HyperTransport and Intel’s QPI (QuickPath Interconnect) and DMI (Direct Media Interface).

back side bus

The speed between the CPU and the L2 cache located outside the main CPU but on the same chip.

PCI bus speed

The speed at which data is delivered when the PCI bus is being used. Common speeds for the PCI bus are 33 and 66MHz, allowing bandwidths up to 533MB/s.

PCIe bus speed

The speed at which data is delivered when the PCIe bus is being used. This bus is the main bus used on the motherboard and is used for PCIe adapters. Common speeds for the PCIe bus v2.x are from 500MB/s (x1) to 8GB/s (x16), v3.x are from 985MB/s (x1) to 15.75GB/s (x16), and 4.x are from 1969 MB/s (x1) to 31.51GB/s (x16).

AGP bus speed

The speed at which data is delivered when the AGP bus is being used. The AGP bus is an older standard used for video cards.

CPU speed

The speed at which the CPU operates; it can be changed on some motherboards.

CPU throttling

Reducing the clock frequency to slow the CPU in order to reduce power consumption and heat. This is especially useful in mobile devices.

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