I have a Rev 2 board, I tried all the other DSDTs posted on this thread, but one I had originally used on a Rev 1 board worked best for me (lower temps and better overall functionality). I have everything working including Sleep. Only problem, of course, is that the Ethernet only works in 32-bit. Workaround is to get a cheap $10 PCI Ethernet card or a cheap $10 Wireless USB Adapter. (I'm using wireless).
I'm betting a lot of issues people are having are related to driver installations and not only DSDT. This is what I did to get my rig up and running:
I did a fresh install from an existing Mac. Used UInstaller to install 10.6, then the 10.6.4 combo update. Then used Multibeast to install all the necessary drivers, these are the options I checked under the "Advanced Options Tab" in Multibeast:
Kexts-‐-‐-‐-‐>Audio-‐-‐-‐>LegacyHDA-‐-‐-‐>
ALC889
Kexts-‐-‐-‐-‐>Audio-‐-‐-‐>HDAEnabler-‐-‐-‐>
ALC889
Kexts-‐-‐-‐-‐>Audio-‐-‐-‐>
AppleHDA 10.6.2
Kexts-‐-‐-‐-‐>Disk-‐-‐-‐>
IOAHCIBlockStorageInjector (fixes the orange hard drive icons)
Kexts-‐-‐-‐-‐>Graphics-‐-‐-‐>
NVEnabler
Kexts-‐-‐-‐-‐>Network-‐-‐-‐>
RealtekR1000SL (doesn't really help us Rev 2 people, but good to have anyway...)
Kexts-‐-‐-‐-‐>Miscellaneous-‐-‐-‐>
fakesmc
Chameleon-‐-‐-‐-‐>
Chameleon 2.0 RC4
com.apple.boot.plist-‐-‐-‐-‐>
64-‐bit Apple Boot Screen
smbios.plist-‐-‐-‐-‐>iMac11,1-‐-‐-‐>
Core i7
Themes-‐-‐-‐-‐>
Standard Chameleon
I then copied my DSDT into the Extra folder, and also over-wrote the 'smbios.plist' file in Extra with one that identifies the machine as the latest Mac Pro, but with an i7 processor. My DSDT and smbios.plist files are attached to this post.
Note about Video: I was originally using a 9800 GT. But it had annoying issues. It hooked up fine to my monitor through DVI, but as soon as a used a DVI-to-HDMI adapter to take it to my TV, the screen went blank after the Apple boot logo. I looked it up and turns out that's a common issue with a lot of video cards (and I couldn't find a single fix). I also tried a GTS 250 and got the same issues (works fine with DVI, but no-go on HDMI). So I stick with my GT 240 'cause it just plain works without any extra futzing. A 9500 GT is also good too.
Anyway, hope all this helps. If only they came out with 64-bit versions of the Ethernet driver, we'd be set.
You can get Multibeast here:
http://www.tonymacx8.../MultiBeast.zip