Why the switch

[Preti9cboi]

I'm just curious why companies switched from AGP to PCI-E.
Is PCI-E suppose to allow video cards to be faster?

 

[trinibwoy]

 

[trinibwoy]

Video cards will benefit but that's not all. They would've maxed out AGP 8x bandwidth pretty soon as games used more high-res textures so that needed to be replaced anyway. PCIe is full-duplex and just as fast in either direction - AGP was pretty slow when uploading from the GPU to CPU/Mem and could only transmit in one direction at a time. Now that there is a high-bandwidth uplink technologies like turbo-cache and hyper-memory are possible. PCIe is also more scalable (in terms of lanes and speed) and is a point-to-point serial interface so routing the motherboard traces is a lot more straightforward as well. You also don't have any resource contention like there is with PCI since each device has its own dedicated link to the PCIe controller etc etc etc.....

 

[Bateluer]

Originally posted by: trinibwoy
Video cards will benefit but that's not all. They would've maxed out AGP 8x bandwidth pretty soon as games used more high-res textures so that needed to be replaced anyway. PCIe is full-duplex and just as fast in either direction - AGP was pretty slow when uploading from the GPU to CPU/Mem and could only transmit in one direction at a time. Now that there is a high-bandwidth uplink technologies like turbo-cache and hyper-memory are possible. PCIe is also more scalable (in terms of lanes and speed) and is a point-to-point serial interface so routing the motherboard traces is a lot more straightforward as well. You also don't have any resource contention like there is with PCI since each device has its own dedicated link to the PCIe controller etc etc etc.....

In addition, the PCIe bus also supplies more power to the video card, eliminating the need for the 4pin molex power connectors so common to high end AGP cards.

 

[trinibwoy]

Oh yeah. Left out one of the most important things The next PCIe version may even support up to 150W instead of the current 75W. That might not help though since Nvidia's next gen G70 is (very unreliably) rumoured to use 150W+. So the high-end PCIe G70 might still need two molexes!

 

[imported_Noob]

Basically just more bandwidth. That bandwidth will come in handy once AGP 8x bottlenecks the bandwidth required in future games. There is no performance increase as of today. The description trinibwoy gave is more in depth.