Front-End bus frequency and external frequency

The actual operating frequency of the CPU is the product of the outer frequency and the multiplier. The outer frequency is like the width of the road, and the multiplier is like the number of vehicles allowed to pass through the road per unit time. At present, the external frequency of mainstream CPU is usually 66, 100 or 133. For example, pentiumiii 667 means that the external frequency is 133 multiplied by the 5th harmonic increase. Generally, the CPU performance with high external frequency is better, which is why the piii667 with 133 external frequency is equal to that with 100 external frequency piii700. Therefore, when selecting a CPU, you should not only view the total frequency, but also pay attention to the composition of the frequency.
CPU frequency
Anyone who knows about computers should be familiar with the word "Frequency! The CPU usage as the core of the machine is of course very heavy.
Yes, because it can directly affect the performance of the machine. So, do you have a thorough understanding of CPU frequency issues? Please come with me,
Let me give you a detailed explanation!

The so-called clock speed, that is, the clock frequency when the CPU is working normally. Theoretically, the higher the CPU clock speed, the faster the speed, because the frequency
The higher the number of commands completed within the Unit clock cycle, the faster the speed. However, due to the differences in the internal structure of various CPUs
(For example, cache and Instruction Set), the speed is not the same as the clock frequency, for example, piII and sai Yang, Thunderbird and duron, sai Yang and duron,
PiII and Thunderbird have different performance levels at the same clock speed. Currently, the clock speed of mainstream CPUs is above MHz, and the frequency
The highest (not the fastest) P4 has reached 1.7 GHz, AMD's thunderbird has reached 1.3 GHz, and will continue to improve.

After the advent of 486, due to the increasing frequency of CPU operation, some other devices (such as plug-in cards and hard disks) on the PC are working.
Therefore, the CPU frequency is further increased. As a result, the frequency doubling technology has emerged.
It is enough to change the internal frequency of the CPU to a multiple of the external frequency, so as to increase the frequency by increasing the frequency. Therefore, after 486
We are exposed to two new concepts: External frequency and frequency doubling. The relationship between them and the clock speed is the external frequency X multiplier = the clock speed. The external frequency of a CPU and today's
Day we often say that the FSB (front side bus, Front End bus) frequency is the same (note, it is the same frequency), currently on the market
The external CPU frequencies include 66 MHz (SAI Yang series), 100 MHz (some piII and some Thunderbird and all P4 and duron), and 133 MHz (Unit
PiII and part of Thunderbird ). It is worth mentioning that at present, some media have publicized that some CPU frequencies have reached 200 MHz (duron ),
266 MHz (Thunderbird) or even 400 MHz (P4), in fact, is to confuse the outer frequency with the front-end bus, in fact, their outer frequency is still
133 MHz and MHz. However, due to the use of special technologies, the front-end bus can complete two or even four transmission times in a clock cycle,
Therefore, the frontend bus frequency is increased several times. However, from the definition of frequency and frequency doubling, their frequency is not changed accordingly.
I hope you will pay attention to this. Today, the external frequency is not much higher than the original frequency, but the frequency doubling technology has developed to a very high stage.
. In the past, the frequency doubling was only 2-3 times, and the current P4 and Thunderbird have all reached more than 10 times. I don't know if it will be higher in the future.
The current CPU multiplier is usually locked before the factory (except for some engineering samples), while the external frequency is not locked. Some CPUs, such as amd
Duron and Thunderbird can unlock the frequency doubling through special means, while Intel's CPU does not.

Due to the constant increase in the external frequency, it gradually becomes unacceptable to other devices, so the frequency division technology (in fact, this is the main board North Bridge core)
Function ). The frequency division technology is to reduce the CPU external frequency through the North bridge chip of the Main Board, and then provide each plug-in card, hard disk and other devices. Early
In the MHz external frequency era, PCI devices are divided by 2, while those of AGP devices are not. In the later MHz external frequency era, PCI devices are divided by 3.
Secondary 2/3 Frequency Division (some MHz North Bridge chips also support PCI Device 4 Frequency Division); currently, North Bridge chips generally support MHz external frequency, that is
The PCI device is divided by 4 and the AGP device is divided by 2. In short, the North Bridge Chip must enable the PCI device at the standard external frequency (66 MHz, 100 MHz, 133 MHz ).
Only when 33 MHz and 66 MHz are used by the AGP device can the chip officially support this type of out-of-band.

Finally, let's talk about CPU overclocking. CPU overclocking is actually to increase the CPU clock speed by increasing the external frequency or frequency doubling.
System performance. The history of the Super frequency has been very long (in fact, it is also a few years), but what you really like is the production of the Sai Yang series.
In the beginning, the competition between 450 and 366 was over 550. And they are
The external frequency of 66mhz is increased to MHz, thus increasing the CPU clock speed. The early duron superfrequency was different from that of SAI Yang. It cracked the frequency doubling lock.
Then, increase the frequency. In general, the superfrequency is more stable than the superfrequency, because the superfrequency does not change the frequency.
It does not affect the normal operation of other devices. However, if the out-of-band frequency is exceeded, non-standard out-of-band frequencies such as 75 MHz, 83 MHz, and limit MHz may occur,
In these cases, due to the frequency division technology restrictions, other devices cannot work at normal frequencies, which may cause system instability.
, Or even hard disk data loss, serious damage. Therefore, I would like to warn you that overclocking is good but dangerous.
Risks, so please be careful when exceeding the frequency!
The frontend bus is a data channel between the processor and the motherboard's Northbridge chip or memory control hub. Its frequency directly affects the speed of CPU access to memory. BIOS can be seen as a software related to memory computers, you can use it to adjust relevant settings. The BIOS is stored in a chip on the board. The chip is named coms Ram. But like ATA and IDE, most people confuse them.
Because the main board directly affects the performance, stability, functions and scalability of the entire system, its importance is self-evident. The purchase of the motherboard seems simple, but there are many things to pay attention. When purchasing a product, pay attention to the product chipset, working materials, functional interfaces, and even ease of use. This requires a thorough understanding of the motherboard to select a satisfactory product.
A bus is a set of transmission lines that transmit information from one or more source components to one or more target components. Generally speaking, it is a public connection between multiple parts, which is used to transmit information between parts. People often describe the bus frequency at a speed expressed in MHz. There are many bus types. The English name of the front-end bus is the front side bus, which is usually expressed as FSB. It is the bus that connects the CPU to the North Bridge Chip. The front-end bus frequency of the computer is determined by the CPU and the North Bridge Chip.
The CPU is connected to the beiqiao chip through the front-end bus (FSB), and then exchanged data with the memory and video card through the beiqiao chip. The front-end bus is the main channel for data exchange between the CPU and the outside world. Therefore, the data transmission capability of the front-end bus has a great effect on the overall performance of the computer. If the front-end bus is not fast enough, A strong CPU does not significantly increase the overall speed of the computer. The maximum bandwidth of data transmission depends on the width and transmission frequency of all data transmitted simultaneously, that is, the data bandwidth = (bus frequency × data Bit Width) ÷ 8. Currently, the frontend bus frequency on a PC is 266 MHz, 333 MHz, 400 MHz, 533 MHz, or MHz. The higher the frontend bus frequency, it indicates that the greater the data transmission capability between the CPU and beiqiao chip, the more CPU functions can be fully utilized. The current CPU technology is developing rapidly, and the computing speed is increasing rapidly. The large enough front-end bus can ensure that enough data is provided to the CPU. The low front-end bus cannot supply enough data to the CPU, this limits the CPU performance and becomes a system bottleneck.
The speed of the bus between the CPU and the North Bridge Chip represents the speed of the CPU and external data transmission. The concept of external frequency is based on the fluctuation speed of Digital pulse signals. That is to say, a 10 thousand MHz external frequency refers to a digital pulse signal that oscillates million times per second, it affects the frequency of PIC and other bus. The two concepts of Front-End bus and external frequency are easy to confuse, mainly because for a long time ago (mainly before the appearance of pentium4 and when Pentium 4 was just launched ), the frequency of the front-end bus is the same as that of the outer frequency. Therefore, it is often called the front-end bus as the outer frequency, which leads to such misunderstanding. With the development of computer technology, it is found that the frequency of the front-end bus must be higher than that of the outer frequency. Therefore, QDR (quad date rate) technology or other similar technologies are used to achieve this currently. The principles of these technologies are similar to the 2x or 4x of AGP. They make the front-end bus frequency twice, 4x, or even higher than the outer frequency, since then, the difference between the front-end bus and the external frequency has been paid attention.
Frontend bus frequency
A bus is a set of transmission lines that transmit information from one or more source components to one or more target components. Generally speaking, it is a public connection between multiple parts, which is used to transmit information between parts. People often describe the bus frequency at a speed expressed in MHz. There are many bus types. The English name of the front-end bus is the front side bus, which is usually expressed as FSB. It is the bus that connects the CPU to the North Bridge Chip. The front-end bus frequency of the computer is determined by the CPU and the North Bridge Chip.

The beiqiao chip is responsible for connecting the components with the highest data throughput, such as memory and video card, to the nanqiao chip. The CPU is connected to the beiqiao chip through the front-end bus (FSB), and then exchanged data with the memory and video card through the beiqiao chip. The front-end bus is the main channel for data exchange between the CPU and the outside world. Therefore, the data transmission capability of the front-end bus has a great effect on the overall performance of the computer. If the front-end bus is not fast enough, A strong CPU does not significantly increase the overall speed of the computer. The maximum bandwidth of data transmission depends on the width and transmission frequency of all data transmitted simultaneously, that is, the data bandwidth = (bus frequency × data Bit Width) ÷ 8. Currently, the frontend bus frequency on a PC is 266 MHz, 333 MHz, 400 MHz, 533 MHz, or MHz. The higher the frontend bus frequency, it indicates that the greater the data transmission capability between the CPU and beiqiao chip, the more CPU functions can be fully utilized. The current CPU technology is developing rapidly, and the computing speed is increasing rapidly. The large enough front-end bus can ensure that enough data is provided to the CPU. The low front-end bus cannot supply enough data to the CPU, this limits the CPU performance and becomes a system bottleneck.

The difference between the external frequency and the front-end bus frequency: the speed of the front-end bus refers to the speed of the bus between the CPU and the North Bridge Chip. More importantly, it represents the speed of the CPU and external data transmission. The concept of external frequency is based on the fluctuation speed of Digital pulse signals. That is to say, a 10 thousand MHz external frequency refers to a digital pulse signal that oscillates million times per second, it affects the frequency of PCI and other bus. The two concepts of Front-End bus and outer frequency are confusing, mainly because during a long period of time (mainly before the emergence of Pentium 4 and when the emergence of Pentium 4 ), the frequency of the front-end bus is the same as that of the outer frequency. Therefore, it is often called the front-end bus as the outer frequency, which leads to such misunderstanding. With the development of computer technology, it is found that the frequency of the front-end bus must be higher than that of the outer frequency. Therefore, QDR (quad date rate) technology or other similar technologies are used to achieve this purpose. The principles of these technologies are similar to the 2x or 4x of AGP. They make the front-end bus frequency twice, 4x, or even higher than the outer frequency, since then, the difference between the front-end bus and the external frequency has been paid attention.