Understanding the Speed of the Pci Express Data Bus

By: Otis Cooper

The personal computer is constantly changing with such component upgrades for memory,cpu speed and hard drive capacity.And the video display is no exception.

The video display consist of a Graphics Card, Monitor,and the Bus.If you're wondering what the heck is a Bus in any video display,its the data path along which data moves into, out of, and inside the the computer.

This data is sent from the motherboard and central processing unit, to the graphics card,travels along the data path or Bus, to the Monitor where our eyes can see it.The data Bus is partly responsible for our clear and fast the graphics of our favorite games are displayed.

It does not matter how fast the CPU chip or graphics card can send data if the Bus becomes too small and prevents the data from traveling fast.This causes a bottleneck of data when the graphics card sends data faster then the Bus can allow it to travel.

The first Bus was introduced by IBM or International Business Machines and was called the ISA.The Industry Standard Architecture Bus was slow and weak since it sent data at just 4MHz.

But it was matched with the CPU chip of that day.The average cpu speed during this time was around 4.77MHz. This bus came in 1981 and IBM created a faster bus soon after with a 16 bit bus with a cpu speed of 8 to 10 MHz three years later.

By this time many other computer makers were building Computers using the IBM design and IBM quickly responded to the competition by making a proprietary
bus called the MCA or Micro Channel Architecture.

When IBM built proprietary Buses they mean they built hardware or software, in this case Buses, owned and controlled by a single individual or organization.

The Bus technology came about in the following order.

1983 IBM introduced the ISA Bus and in 1984 the faster 16 bit ISA Bus arrived.Then in 1987 the 32 bit MCA Bus showed up.And in 1988 Compaq and other PC makers released the 32 bit EISA or Extended Industry Standard Architecture bus

1993 brought us the Video Electronics Standards Association or the VESA Bus.This year also allowed the release of the PCI or Personal Computer Interconnect Bus.

And in 1996 came the AGP or the Advanced Graphics Port while 1998 brought us the AGP 2.0 and in 2002 came the ,you got it, the AGP 3.0 data bus.

Finally in 2005 Intel and AMD introduced computers running at speeds of 4Gigabytes or more.At these speeds the AGP port presented at slowdown for the data.

So the folks at Intel put their heads together and came up with the PCIe.The Personal Computer Interconnect Express.The bus is like the PCI but uses a serial port whereas the PCI use parallel ports.

Parallel ports send data in chumps and Serial ports send data one at a time.With the PCI bus, each slot share a maximum of 132MB a second and the PCIe allow each slot to have 250 Megabytes a second to send data.

PCIe is intended to be used as a local interconnect only.As it is based on the existing PCI system, cards, and systems can be adapted to PCI Express without any change in software.The higher speeds on PCIe allow it to replace almost all existing buses.
Nearly all high end graphics cards today in 2006 from AIT and NVIDIA use PCI Express.And Nvidia use the faster data transfer of PCIe for their SLI or Scalable Link Interface technology.
This technology allow two graphics cards of the same chipset and model number to be ran at the same time. This greatly boost performance like you never thought possible.
Not to be out done, ATI came on the scene with their dual GPU system or Graphics Processing Unit called the Crossfire.

As you can see, the PCI Express bus is faster and if possible, when purchasing your next computer, be certain it comes with PCI Express slots.

The AGP data bus was fast compared to the PCI but they are both fading away.So it is very beneficial to you if you get to know and understand the PCIe in every detail.

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