I have this Tyan S2567 motherboard running dual Tualatin CPUs. While there is an ACPI option to enable in the BIOS, Windows (w2k & XP) complains that my motherboard is not fully ACPI compliant and will not install. To install Windows, I need to tell the Windows installer that I'm using an MPS Multiprocessor PC instead of an ACPI Multiprocessor PC. Once Windows using the MPS HAL, it doesn't matter if the ACPI option is enabled or disabled in the BIOS.

The most prominent visible disadvantage to MPS is that when you go to shutdown your computer, you are greeting with an old NT4 type shutdown screen saying that it is now safe to turn off your computer, at which point, you press the power button.

Is there any other disadvantage to MPS over ACPI? In my mind, MPS is the multi-processor variant of the "Standard PC" HAL. I thought this would mean that my IRQ's were limited to 15, but that isn't the case according to the resource manager.

Is there a workaround to get W2K and XP Pro to soft-shutdown? I see some hack for NT4 which I haven't tried yet, https://nt4ref.zcm.com.au/softoff.htm