Originally Posted by zander
The sysctl OID for the AGP rate would be hw.nvidia.registry.ReqAGPRate, but it's disabled by default. You'd need to edit src/nvidia_os_registry.c after extracting the NVIDIA driver .tar.gz archive and enable the key in the nv_parms table befor executing `make install`.
I probably have to play around with this on my AMD64 system as it doesn't have a BIOS option to lower the AGP rate.
Lowering the rate (in the BIOS) on my dual athlon works btw. It hasn't frozen since. I'm currently running it with the NVidia AGP driver.