OS in APIC mode, can't warm boot

[mikeblas]

I have an Asus P6T6 WS Revolution board that won't warm boot. If I cold boot, the machine restarts fine.

If I restart from Windows or by holding down the power button without first removing power, the machine restarts, the keyboard lights flash, then the machine hangs with a black screen. None of the PCI cards have initialized at this point, and I haven't seen any messages from the BIOS.

The G.P. Diagnosis board shows the code "AA", which the manual says means "OS in APIC mode". After a successful boot, the card shows "01".

How do I repair this problem?

 

[mikeblas]

I'm finding that this problem is getting worse; I sometimes can't reboot after removing power and going cold. I've also noticed that the OS doesn't seem to be involved; if I enter the BIOS and fuss with settings there, then save and reboot, the machine won't reboot.

I've tried turning off the APIC modes in the BIOS and that doesn't help.

I believe my Areca card is related to the issue as I hear it beep twice at reset when the machine will boot successfully, but only hear one beep at reset when the machine will not boot. However, I've temporarily removed the card and it does not change the symptoms.

What choices do I have for diagnosing this issue?

 

[mikeblas]

I ended up discovering that setting "APIC in 2.0 mode" to "YES" in the BIOS cures this problem. I can't find any documentation on this setting, and simply stumbled up on it by trial and error.