metrons, have you got this working since your post? If not, I'd take out the graphics card and boot with -v PCIRootOption=0. Booting with the -v option shows you what's going on and how far it gets into the boot process. I've just installed ML 10.8.5 on my system, ASRock Z77 Extreme4-M in the last day and have it working, so might be able to help a little.
I know this post is a couple of months old, but I thought I'd start here ... I have an Asrock z77 extreme4 board, with a 2600k, 16gb (4x4gb) of ram, Sandisk 120gb SSD (not using for Mac - Win 8.1 is installed there), a WD 1TB HDD for Windows storage, a 500GB Samsung (which is where Mac OSX will reside), and a GTX 770 (ACX, if that matters).
I have been at this for a couple of days now... I tried to install Mavericks on to the 500gb drive, from a 320gb external drive I prepared using Unibeast. I say tried, but I can load Mavericks and run Multibeast, and I assume I am ticking all the correct boxes (trying to follow the guides as best I can - although not many detailed ones that I have found related to Multibeast for Mavericks). After clicking "Install" at the end of multibeast and rebooting the computer, I get to the grey screen with the Apple logo and the grey cheerio, but the loading indicator (grey cheerio since I don't know the actual name of it) freezes and I get a kernel panic message. The one I have seen the most is related to AppleIntelPowerManagement.
In Multibeast, I know there is an option to either remove (the "Null.." option) it, or I can patch it. Well, I have done both, but I still cannot get into the OS after that reboot.
I should also mention that I am running a modified BIOS (2.70) that I found the link to here in the forums. Also, I have done the complete install will all ram and my video card in. When I initially get into Mavericks (before running multibeast) everything works except my audio and my ethernet, but I use a tp-link wireless card so the latter is not a big deal.
Any guidance/help would be appreciated. Also, if I run into the kernel panic again, do I have to erase the partition and reinstall the OS again, or is there some kind of restore I can run that may be a little quicker?
Thanks,
Cameron