The following Snow Leopard installation method to the Gigabyte EP45-UD3R is not my work, simply a compilation of two different methods, one by Adam Pash, editor of Lifehacker and the other by d00m42. They have done amazing work and derserve much credit. All Ive done is copy/paste bits and pieces of their work (along with many of my own tweaks) to make something that enabled me to successfully install Snow Leopard onto a Gigabyte EP45-UD3R motherboard. And it works perfectly...no Kernel Panics. This method only works on the EP45-UD3R motherboard, I wouldnt try it on any other as the DSDT.aml is specifically setup for the EP45-UD3R. For this method to work, you must have an operable version of OS X already installed on another computer, an empty HDD, and a portable USB Hard drive for the installation. Also, Youll need to download this file onto your existing OSX installation (many thanks to d00m42 for this bit of genius).


Step One: Prepare Your USB Drive
We are going to be installing Snow Leopard to your Hackintosh from your USB drive rather than from the Snow Leopard install DVD, since in order to run the installer on your PC to begin with, youll need to slightly customize the way the installer is loaded. (More specifically, we will be loading a custom bootloader onto the USB drive that will make booting into the install work like a charm.*)
So first things first: You need to format your USB drive and then turn your Snow Leopard install disc into a disk image on your desktop. Here is how to do it:
1. Launch the Disk Utility application another OS X Leopard computer: (located at /Applications/Utilities/Disk Utility)
2. Format and partition your USB drive: Insert your USB drive; after a second, it should show up in the Disk Utility Sidebar. When it does, (1) click on it, then (2) click on Partition. (3) Choose 1 Partition from the Volume Scheme, (4) give it a name (I called my HackintoshInstall) and select Mac OS Extended (Case-sensitive, Journaled) from the Format drop-down. Now, and this is important: (5) hit the Options button and make sure GUID Partition Table is selected as the partition scheme. Once youve made sure to set all the appropriate settings, just (6) click Apply and Disk Utility will get to partitioning your USB drive.
3. Copy the Snow Leopard Install DVD image to your hard drive: In the following step we will be turning your USB drive into Snow Leopard Install drive, but before we do that, we need to get the installer off your DVD and onto your hard drive. To achieve this, insert the Snow Leopard DVD. When it shows up in the Disk Utility sidebar, (1) click on it, then (2) click New Image in the Disk Utility toolbar. Choose where you want to save it (for the sake of convenience, I put it on my Desktop), then click the Save button. Now go grab yourself a cold drink. This will take some time. When it finishes, move on to the next step.
4. Restore the Snow Leopard Install disk image to your USB drive: Now, in Disk Utility, (1) click on HackintoshInstall (or whatever your called your partitioned USB drive) and (2) click on Restore. (3) Drag and drop Mac OS X Install DVD.dmg from the sidebar to the Source field, then (4) drag and drop your USB drive from the sidebar to the Destination field. Now simply (5) click on Restore and enter your password when prompted. Disk Utility will take everything on the Snow Leopard Install DVD and restore that image to your USB drive since, like I said above, we will be installing Snow Leopard from our USB drive instead of the DVD. Again, go grab yourself another drink; this will take a few minutes. When it finishes, your USB drive has basically been turned into a Snow Leopard installation drive.
5. Dont reboot yet; Run PC EFI 10.1 from the SL Pack, and install it to the HackintoshInstall USB drive. Then copy all items from the Extra folder on the SL Pack into the Extra folder in the HackintoshInstall USB drive.
5a. Lastly, copy and paste the entire SL Pack folder onto the HackintoshInstall USB drive (for later use).

Step Two: Prepare your EP45-UD3R BIOS
6. Boot into BIOS of the EP45-UD3R and go to "Integrated Peripherals" menu. Set SATA RAID/AHCI Mode to AHCI mode.
7. Also in BIOS in "Advanced BIOS Features", select your USB hard drive as 1st boot drive in Hard Disk Boot Priority. Save and Reboot.

Step Three: Install Snow Leo from the USB drive to your HDD
8. Now you are ready to install the OSX-SL onto your hard drive (not your USB dirive). Reboot hitting F12 to make sure to select your USB drive in Hard Drives. Select (enter) the HackintoshInstall icon when the GUI appears. When the installer boots, go to Disk Utilities and setup your HDD that you want to install Snow Leopard onto; make sure youve re-partitioned it, GUID formatted HDD, name it: Snow. Complete the rest of installation as usual...it will take 15-30 minutes.
9. When install is complete, reboot.

Step Four: Tweak the new Snow Leo installation
10. Reboot again to your HackintoshInstall USB drive using the F12 method to select the USB drive. But this time, when the GUI appears showing the HackintoshInstall USB drive, use the arrow keys to select your newly created Snow HDD.
11. Hopefully it boots into your new version of Snow Leopard. Go through all the normal initial setup screens. Then, go to your USB drive/SL Pack and agian run PC EFI 10.1, but this time make sure to install it to your newly installed Snow Leopard installation on the Snow HDD.
12. Next, copy all the contents of the Extra folder in the SL pack, and paste to into the Extra folder in the root of your Snow drive.
13. Next is to manually edit the UUID of the Snow drive into two different locations. First, open the "smbios.plist" (from your Extra folder) in PlistEdit Pro. Fill in the information in the <string> tags, although it's not necessary to have a serial number. The plist is currently configured for a Mac Pro 3,1, but you can use whatever you want, look up a guide on smbios.plist. The SMexternalclock is your FSB speed, the SMmaximalclock is your processor speed in MHz, the SMmemtype is your memory (18 is DDR, 19 is DDR2, and I think 20 is DDR3), and finally SMmemspeed is your memory clock in MHz. Now, without closing smbios.plist yet, open Disk Utility. Click on your Snow drive, and then on Info at the top. Copy the Universal Unique Identifier string, and paste it into a new text file, because you will use this later on as well. Close Disk Utility, and proceed to paste the string you just copied into smbios.plist under SMUUID on top of the "PASTE YOUR UUID HERE". Once you have completed this, save the smbios.plist, make sure the changes were applied, and navigate back to your Extra folder.
14. This time, go into Extensions, and right click on PlatformUUID.kext, picking the "Show Package Contents" option. Open the Contents folder, and finally open Info.plist with PlistEdit Pro. Copy your UUID again, and paste it over where it says "PASTE YOUR UUID HERE". Save the changes, and close the window.
15. Next, open up EFIStudio, located in the SL Pack. Select your Graphics card, and hit "Add Device". Copy the long hex string in the second (lower) box of the new window that pops up. Open up com.apple.Boot.plist in your Snow drive's Extra folder (with PlistEdit Pro), and paste that long hex string you copied over the long hex string already there (mine). Save the file, and close the window.
16. Lastly, reboot back into BIOS Advanced BIOS Features and select your Snow drive as the 1st boot drive in boot priority, save and reboot. You can lose the USB drive at this point.

Step Five: Boot to a Perfect Snow Leo Hackintosh on the Gigabyte EP45-UD3R
17. Snow Leo should now be perfectly installed. Probably a good measure to run Kext Utility from the SL Pack.
18. Not common, but if you are getting KPs and you have other NTFS Windows HDDs attached to the motherboard, re-boot into SL and quickly disable Spotlight's indexing by adding the NTFS Winows storage devices to the "Private" list in System Preferences>Spotlight. This is NOT an issue on my particular setup and I have two ntfs partitions with full Spotlight functionality and no KPs.
19. I also disabled Software Update automatic checking for updates, as Ive seen KPs associated with this, I DONT USE SOFTWARE UPDATE.
20. UPDATE 1: if you get the stuttering mouse movement issue after launching iTunes or Quicktime, this may likely be because you have a GeForce 8800 GT like me. The Fix: just go to System/Library/Extensions folder and delete AppleUpstreamUserClient.kext. But make sure to run Kext Utility from the SL Pack immediately after you delete this kext and before you reboot (see no. 21 below).
21. UPDATE 2: if you delete any kext from the System/Library/Extensions folder, make sure run Kext Utility from the SL Pack before you reboot. If you don't you may get stuck in an infinite KP loop after reboot.