How can I tell if AGP 4x is really working or not? What software can I run that'll measure the AGP capabilities?
There are a couple of tools out there that will do the job... But to be honest, it's really going to be a wash. Entech (I think) gives Powerstrip (I would be in Linux, else I'd send you the link). Unless you are using DDR or faster memory, AGP 2x is still within the specs of the transfer rate... There were a couple of big writeups done on the hardware sites when 4x was new.... Basically, Nothing aside from a FEW custom q3a levels even comes close to using that much bandwidth on your video bus for texture transfers.... Everything is done now with the local texture memory on the video card.
I *THINK* I saw a 1fps improvement switching 4x on and off. And I'm not sure if it was faster with or without at this point.
If it's doing good, chances are, it's at least 2x, which is really all you need to worry about....
AGP 2x, 4x, et. all are a lot like the x rating on the cdroms... Sure, it will DO that... under these circumstances, on the outside of the disc, if the disc is perfectly clean.... Only change it to be WITH the right drivers, and fast enough main memory, and no significant load on the processor (agP... It's a direct port on the processor, not a bus), and the bios support, no fast writes, etc....