A lot of video boards have been claiming AGP 4X support for quite some time now. However, there really hasn't been any platform to take advantage, let alone test this 4X AGP functionality. Anyone who already has a video board and is planning on making the expensive upgrade to an i820 based platform (when available), or is planning to purchase a board might want to make sure the product they choose supports AGP 4x. Even though a particular chipset, such as NVIDIA's TNT2, supports 4X AGP. If 4X AGP support wasn't implemented in the video board design, that video board may not support it. Even though 4X AGP really doesn't show us any huge performance gains right now. If you are planning to purchase a product in the near future you might want to make sure it does. Obviously the best way to determine if your video solution supports 4X AGP is to check with the manufacturer of the board. Otherwise usually you can tell if the video board supports 4X by looking closely at the edge connector of your video adaptor. Check out this picture.

Example: Video board that supports AGP 4x

A close look at this Diamond Viper V770 Ultra shows the extra notch required for AGP 4X support. The Diamond V770 also includes a jumper that has to be set to enable 4X AGP.

Example: Video board that doesn't support AGP 4x

This Creative Labs TNT2 Ultra board doesn't have the required notch to support 4X AGP.

Again, this is a pretty sure shot way to determine if your board supports AGP 4x or not. But it is always best to check with the board manufacturer to get their boards exact specifications.