APM or ACPI???

I am looking for help on power management. I want to get my LCD to turn off and have beem unable to do do, with several different computers under Mepis. Both have SIS 745 chipsets. During boot ACPI loads and overides APM. I configure to suspend under display options with no effect. If I try to disable ACPI by setting it off in menu.1st it has no effect. ACPI continues to overide APM. If I make aware of power management under dislay options my screen save won't turn on. These are both desktops, so I don't really need anything other than for the backlight to turn off. Do I need to disable ACPI? If so, ho can I force it off? Or, it this chipset just not compatible?

-Ryan