I installed Mandrake linux on a a7n266-vm which has the nforce chipset.
Everything was OK except for the integrated ethernet, which was abysmally slow (10K/sec) but CPU usage was 100%.

I finally tracked this down to ACPI, which causes all sorts of strange problems under linux when the nVidia drivers are installed. Problems range from slow ethernet to X Windows not working.

The solution is the set ACPI=OFF when booting the linux kernel and all the problems magically disappear.

gtoomey