Just wanted to post my experience here; I've always been encouraged by MacMan and Tony's builds, so I always look at their recommended list before diving in.
My first Hack build was the EP45-UD3P with the quad-core Q9650 and nVidia 9500GT. It was flawless; with the basic MultiBeast setup I didn't even need a DSDT till I garnered a better understanding of the system. Unfortunately, the board and CPU were used; I suspect a latent defect because I got random reboots and eventually the system started hanging until it wouldn't even boot any more. I'll skip the whole troubleshooting narrative, but it appears that both the CPU and the mobo have problems.
Instead of trying to find another set of outdated hardware, I decided the time was ripe to go to an X58 series board. I could re-use everything except the RAM (that got migrated to another memory-starved machine) and had the GA-X58A-UD3R already in anticipation of a follow-up build, so the cycle time was very quick; in just a couple of days I had the machine ready to go. Amazingly, it booted from my old HDD, incompatible DSDT and all. I used that to get the OS X installer running so that I could load appropriate kexts, etc. for the new board.
This led to the only problems I had during the process; the machine booted perfectly without DSDT and all I had to do was roll back the HDA stuff to get it working. But I wanted full functionality, so I downloaded the appropriate DSDT from here (rev 2, BIOS FB) and updated the MultiBeast install. Bam - kernel panic. I double-checked, downloaded and re-installed - nada. With some experimentation I found that the FD BIOS DSDT worked, but it made me nervous to use the wrong version. So I got the DSDT editor, took a raw DSDT from my system and processed it. Success! Power management, sleep/wake, and everything. USB, Firewire, even my wireless card works without a hitch.
I've just ordered a Z68 board so I'll have a second system for the office. The X58A was supposed to be my second system until the original one died...