The CPU ratio is the ratio of the speed of a personal computer's central processing unit with that of the computer's system bus. Semiconductor company Intel Corp. in particular refers to it as bus/core ratio, which is a combination of the speeds of the components involved: the core(s), or processing units, that comprise the CPU and the system bus.
Description
Each CPU, which is the part of the motherboard-installed microprocessor, carries out the PC's basic operations at a certain speed; this rate is called clock speed. The system bus -- a computer interface that connects the CPU with other components of the PC such as random-access memory (RAM) -- also runs at a certain speed. The CPU uses the system bus rate to perform at a faster rate than the system bus itself, which it accomplishes by synchronization. This means that it operates in unison with the system bus, thus using it as a sort of timer.
Clock Multiplier
Integral to the CPU ratio is the clock multiplier, also known as CPU multiplier or clock ratio. The clock multiplier, true to its naming, multiplies the speed of the CPU compared to that of the system bus. For instance, if there is a 10x multiplier, the CPU runs at a speed 10 times that of the system bus, and the CPU ratio is written as 1/10. Thus, the involvement of the clock multiplier creates the CPU ratio.
Bus/Core Ratio
For CPUs from companies such as Intel, the CPU ratio is expressed as the bus/core ratio. It is typically represented by a two-digit number, which signifies the clock multiplier. For instance, the Intel Core i7-2620M -- one of Intel's top-level consumer-oriented microprocessors -- has a bus/core ratio of 27 and a clock speed of 2.7 gigahertz, or 2,700 megahertz. Thus, the system bus rate is 100 MHz, which is derived from dividing the clock speed by the CPU multiplier.
Overclocking
Some computer system permit users to increase the clock multiplier -- and consequently widening the CPU ratio -- in the basic input/output system (BIOS) menu. This results in the CPU running at a faster rate than the default standard. This process is known as overclocking. The benefit is a performance boost without the need to purchase additional software. It is a practice particularly popular among PC gamers, who need high-performance machines for their gaming activities.
Tags: clock multiplier, clock speed, ratio clock, certain speed, clock multiplier, computer system, core ratio