Hi all, I'm trying to troubleshoot my way thru a ACPI-issue on several machines with the Asus P5N32-E SLI motherboard (S775, Nvidia 680i chipset) http://www.asus.com/products.aspx?l1=3&l2=11&l3=397&l4=0&model=1459&modelmenu=1 This is CentOS 4 x86_64, and appears on all tested kernels, including kernel-smp-2.6.9-67.0.4.EL My symptoms are that the machine won't reboot on the reboot command. 'poweroff' does turn the power off and halt halts the system (without turning the power off), but reboot effectively does a 'halt'. I can 'fix' this by giving the 'acpi=off' parameter to the kernel in grub, but this causes other problems (some of these machines have quad-core CPUs, and these require ACPI to initialize 3 of the cores. The dual-core CPU-machines work with acpi=off. With acpi=off, reboot works as it is supposed to. I think the root of this issue is the Asus BIOS - we also have several Asus M2N-SLI Deluxe (Athlon64, Nvidia 570 chipset) systems that started exhibiting the same symptom after a BIOS upgrade. On these acpi=off does not cause other problems, so this is no issue for us now. Any suggestions? I think I understand that turning ACPI off basically turns APM on, and that APM reboot works. Is there a way to do reboot with APM instead of ACPI? Yours, -S -- Simen Thoresen - Dolphin ICS Systems Administrator