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After reading some on this forum it occurred to me that some of the people here seem to think that PCI express is just the new way to connect your graphics cards.

PCI express is a bus, just like AGP, CMR, PCI, and ISA. It is serial in nature(think firewire, usb, your mouse/keyboard). You can think of this as if it transmits one command at a time, rather than parrallel(many commands at the same time). PCI express is designed to replace both AGP and PCI.

It will replace AGP, not because it is faster(although it has potential to become much faster), but because it is more flexible. The difficulties involved in putting more than one AGP port on a motherboard are staggering(on the other hand one may question why more than one would be needed).

The new bus isn't expected to replace PCI right away. In fact, its designers expect PCI to be around for a while still. This is because most hardware doesn't currently need nearly the bandwidth that PCIe provides. They think PCI will stick around untill the next widely used form factor is created. Because of this, they made PCIe so that it is exactly the same from a programming standpoint. There is no difference in creating a driver for a PCIe board than there is to create a PCI board. This is so that makers of current PCI cards can switch over to PCIe with little hassle when they decide to do so.

There are many uses for PCI express. Graphics is one, of course, but sound could easily eat up some more bandwidth. Gigabit ethernet is already right near the limit of what PCI can do, so imagine 10Gb ethernet or even near the limit of PCIe: 100Gb ethernet.

For more reading try these(and don't ignore the links on those sites):

http://en.wikipedia.org/wiki/PCI-Express

http://www.anandtech.com/systems/showdoc.html?i=1830

http://www.pcisig.com

http://www.intel.com/technology/pciexpress/devnet/

ps: sorry for the disconnected nature of this post, I have had 5 hours sleep in the past 13 days.

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Parallel interconnect does not mean that it sends multiple commands at the same time.

Commands come after each other

32-bit PCI transfers 32 bits in parallell. If it want to transfer 128 bits then it has to transfer 32 bits 4 times.

The previous command must be transferred before the next one, that applies to PCI, PCI-X, PCIe, AGP, ISA etc.

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  ANova said:
It's replacing AGP because it's faster, being more flexible is just an added advantage.  If it weren't faster they wouldn't be using it.

I agree its simple if its faster then why not? I don't think I agree with:

  Quote
"(although it has potential to become much faster)"

It doesn't have the potential to become faster its already at a specified rate of data transfer. Hence the 1, 4, 8 and 16x physical connectors.

x1 500MB/s

x4 2 GB/s

x8 4 GB/s

x16 8 GB/s

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  Adnan248999 said:
I agree its simple if its faster then why not? I don't think I agree with:

It doesn't have the potential to become faster its already at a specified rate of data transfer. Hence the 1, 4, 8 and 16x physical connectors.

x1 500MB/s

x4 2 GB/s

x8 4 GB/s

x16 8 GB/s

It Transfers 8GB/s in both Directions at the same time. AGP 8x transfers nearly as much - but only in one direction, from Mainboard to the Card. In the other direction the transfer is between 256 and 512 MB/s (if I remember right).

PCI Express also alows to add an 4x1, 2x2 or 1x4 Lane connections ... there are eaven boards with more - 1x16 Lanes an 1x8 Lanes on the Boards needed for the SLI solution from nVidia.

Its a bit sad that we all have to buy new Hardware - but I'm exited about it!

But remember - only start buying PCIExpress Cards, when they are native! Bridged cards are't faster... just like the SATA Harddisks ... ;)

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They think PCI will stick around untill the next widely used form factor is created.

You're referring to the BTX (Balance Technology eXtended) form factor. Since this article was released, PCI Express has become a lot closer to us. In fact, Dell is already shipping PCs with PCIe cards and Intel's Grantsdale chipset. I was suprised that the Grantsdale chipset mobos came out as ATX form factor, thinking PCIe and BTX would be released at the same time. Where's BTX?

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PCI Express 16x = 16 lanes with a throughput of 80GB/s.

PCI = 133MB/s

"In practice, due to embedded clock overheads, the 16x interface gives 8GB/s graphic data throughput in comparison to AGP's 2.1GB/s". That 8GB/s is divided into 2 sets of 4GB/s (one going in each direction), so the max you will be getting out of your gfx card (data wise) will be just about double what you would get out of a AGP card.

It should be a lot faster, although mentioned in the article of the magsaine i got this out of it says that CPU's are the limiting factor at the moment, not the method of transport to and from the graphics card.

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  Zero1 said:
PCI Express 16x = 16 lanes with a throughput of 80GB/s.

PCI = 133MB/s

"In practice, due to embedded clock overheads, the 16x interface gives 8GB/s graphic data throughput in comparison to AGP's 2.1GB/s". That 8GB/s is divided into 2 sets of 4GB/s (one going in each direction), so the max you will be getting out of your gfx card (data wise) will be just about double what you would get out of a AGP card.

It should be a lot faster, although mentioned in the article of the magsaine i got this out of it says that CPU's are the limiting factor at the moment, not the method of transport to and from the graphics card.

That was what I thought too.

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