I have FC4 running on a new Intel D945PVS mobo & everything works great except the soft-off. I do a normal shut down in Gnome, but have to power down manually after the disks park (which they do). FC4 does the shut down sequence, up to & including the power-off call, but then nothing happens after that. Here is my configuration:

Pentium D cpu
Intel D945PVS mobo
4 GB DDR2 RAM
2 SATA disks
1 IDE disk
Diamond Radeon X300 PCIE graphics
ATAPI CD RW
ATAPI DVD R
Soundblaster Live PCI soundcard (plus onboard sound)

The only thing I found on the Intel web page about "soft-off" was that all components must be ACPI compatible. I don't think that's my problem, but I don't know for sure. Any help would be very appreciated. Thanks

Is ACPI loading at boot? Check your dmesg and/or /var/log/messages.

The next thing to check is to look for a BIOS update at the manufacturer's web site.

If ACPI looks OK (not disabled for some reason), and your BIOS is current, then check your BIOS configuration to verify that power-off is not disabled.

The last suggestion is to update your kernel. ACPI support is updated as part of the kernel.

Thanks for your suggestions. It turned out that I didn't understand the bios ACPI settings (& I still don't). I just answered every ACPI bios option with a yes (enable) & it started working...