Hardware Drivers :: Win 8 RTM - Can't Sleep / Hibernate Or Shutdown

I just upgraded to Windows 8 Enterprise x64 RTM yesterday, and have noticed an annoying problem that wasn't present under Windows 7 Enterprise x64 (which I was running previously). Specifically, the machine will not sleep, will not hibernate and will not shut down. When any of the three are attempted, they appear to succeed, but then the computer will immediately wake up again. In the case of a shutdown, the computer will actually power completely off and then start right back up immediately. I never used to sleep the machine in Windows 7, but I know the hibernation used to work and certainly shutting down did as well, as I shut the machine down every night.

In the event viewer, I have a Power-Troubleshooter event (ID 1) every time the machine wakes back up from an attempted sleep, hibernation or shutdown, but it always indicates that the wake source is "Unknown." I have tried unplugging every single Ethernet, USB and eSATA cable from the PC until nothing was left plugged in but the monitors, audio out and AC power -- just in case a device was sending a magic packet or some kind of wake-up signal. Even so, I still experienced the same immediate waking problems on shutdown, hibernate or sleep.

I was able to solve the inability to shut down by disabling Windows 8's "Fast Startup" option, which as I understand it uses a kind of hybrid hibernation. Hibernation is not working properly on my system. At least with "Fast Startup" disabled, I can actually shut the machine down. It's a pity though because I really liked Fast Startup's performance.

I've tried installing the authentic manufacturer drivers for my chipset (Intel 975 / ICH7 series), onboard LAN adapters and so forth in case the generic Microsoft drivers were at fault. The specific driver installation seemed to work fine but my problem remains.

Full system specs are in my profile, but it's kind of an old box I put together in late 2006. Core components of possible relevance to this issue are an Asus P5W DH Deluxe motherboard and Seasonic S12 600W power supply. The motherboard is running the very latest BIOS revision (3002). My Windows 8 installation was an in-place upgrade of my previous Windows 7 installation; everything seems to be working fine except for the weird power stuff.

Here's one other thing I should note, which concerns me somewhat as it is related by definition. In the P5W DH Deluxe's BIOS, there is an "ACPI 2.0 Support" option which defaults to "Disabled". Back when I built the machine I left it alone so it has been disabled this whole time. During my troubleshooting of these issues earlier tonight, I decided to try switching it to "Enabled" to see if it would have any effect. It has not fixed the issues at all, but it does make me wonder. Is there any way to tell whether Windows 8 has correctly identified the system as being ACPI 2.0 compliant? I think I remember in the old days WinXP used to have to be completely reinstalled when that switch was flipped.

Additionally, and much to my consternation, I can no longer use Wake On LAN. I've actually fixed the WoL issue. I had to go into Device Manager, find my network adapter and get the properties of it -- then, on the Advanced tab, find the property called "Wake From Shutdown" and set it to "On". This must have been either a new property in the Windows 8 driver for my network adapter, or was reset back to Off for some reason when I did the Win7 -> Windows 8 upgrade.