The people of Extreme Tech have discussed the use of 8X AGP on their site :
With PCI Express on the horizon, AGP 8X (version 3.0) will mark AGP's swansong as the PC's high-speed graphics pipe. But with its wide installed base, AGP will be with us for some time to come, even once PCI Express motherboards and 3D cards/modules become available. AGP 8X brings with it two noteworthy features: a 2X speed increase to 2.2GB/sec and the ability to have more than one AGP graphics device in a system.
Intel has given its blessing to AGP 3.0, but has yet to ship any chipsets or motherboards that support the new standard. Meanwhile, both Via and SiS now have chipsets on the market that support AGP 8X. ATI shipped its Radeon 9700 GPU, which ostensibly supports AGP 8X, although the company has acknowledged that their implementation had some issues when the Radeon 9700 first arrived. nVidia recently shipped its nForce 2 chipset as well as its NV18 (GeForce 4 MX) and NV28 GeForce 4 Ti 4200 GPUs, all of which support AGP 8X.
But the simple question is: does AGP 8X really make a palpable difference in boosting 3D graphics performance?
To find out, we took a SiS 648-based motherboard and nVidia's NV28 GPU for a spin through some benchmarks and uncovered some interesting results.
If you want to just see those results, head to the Conclusions section, otherwise turn the virtual page for our analysis of whether you should rush out and get a new motherboard supporting AGP 8X.