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- Fri, May 17
- Dust: An Elysian Tail hitting PC May 24, the Blade of Ahrah and the power it controls awaits
- PC port of Metal Gear Rising: Revengeance confirmed, no release date given
- The Wonderful 101's not so wonderful release date announced, pushed to September 15
- Trion Worlds, developer for MMOs RIFT and Defiance, suffers heavy layoffs
- Team Fortress' "Robotic Boogaloo" update hits, first to be entirely developed by the community
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Introduction
The venerable PCI Bus has been one of the bastions in PC connectivity for roughly a decade now. The limitations of the PCI bus was first highlighted with the introduction of the ubiquitous AGP port back in the summer of 1997.
The main advantages of AGP are its increased bus speed / bandwidth as well as its point to point architecture. A point to point protocol means that AGP has its own path way to communicate with the processor as well as one to the memory whereas every device on the PCI bus had to share the 133 MB/s worth of bandwidth allocated to it. Both the AGP and PCI Bus are based on a 32 bit bus. AGP being clocked at 66 Mhz versus 33 for PCI had double the bandwidth (266 MB/s) in its first iteration. With the ability to transfer data multiple times per clock cycle, AGP in recent times (currently at a maximum of 8x, has ~2100MB/s of bandwith).
With a bevy of high speed I/O devices today outside of the graphics card including SATA / ATA150 (150 MB/s), Gigabyte Ethernet (125 MB/s), 1394B (100 MB/s) it is easy to see that any one of these devices alone can completely saturate the PCI bus completely. Nearly everything else in the PC has scaled in one way or another in the past decade except for the PCI bus. With the exception of PCI-X (a 64 bit, 66 Mhz, server solution), the PCI bus has stayed relatively stagnant while many of the subsystems have been scaling up (frontside bus speed, memory, AGP). Fortunately, this is about to change with the advent of PCI Express.
PCI Express
PCI Express (not to be confused with PCI-X) is the upcoming replacement for both PCI and AGP. A couple of main points about PCI Express
- While the classic PCI Bus is based upon a parallel architecture, PCI Express is serial based, drastically reducing pin count.
- It is a point to point protocol much like AGP. Devices do not share bandwidth
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Are AGP cards just going to suddenly cease then post launch of PCI Express, or just gradually fade to the back of the shelf like PCI did post AGP launch? Or am I still misunderstanding the whole concept here? My understanding is that PCI Express is the new type of "slot" for expansion cards, making 3 in the hardware industry (PCI, AGP and now PCI Express). If this is incorrect, I'd appreciate being corrected and educated on the subject.
AGP is going to fall off pretty drastically from what I've been hearing. PCI Express is looking to be the main focus for the market by about Christmas. PCI Express is a new type of slot. It will eventually replace both PCI and AGP with AGP being the forerunner on the chopping block. As AGP only services graphics cards it is the easiest thing to axe since both ATI and Nvidia have thrown their lots in for PCI Express. Implementing both AGP and PCI Express has also been a sticking point for a lot of companies so dont hold your breath for a board that supports both
Which is faster?
pci express can scale hence the x1 x2 x4 x8 x16 x32 configuration. in a x1 configuration, PCI-Express provides 500 MB/s in full duplex mode already. Scaling up to x4 and up, PCI Express will trounce PCI-X in terms of bandwidth.
Incidentally, I got hooked on the AMD Athlon processors. I will be coupling a 3000 with a Gigabyte board. I am not big on games, but I do some graphics stuff as a hobby; however, it may become more than a hobby in the future. My friend advised me not to go with the PCI Express, but after reading these four articles, I can predict that my son will say the opposite when I can reach him during normal daylight hours.