You will need the following:

 A Snow Leopard DVD
 A blank hard drive (it can be done on a partition, however)
 An existing OS X install (I used my Leopard 10.5.8)
 My SL Pack
 Patience

**BEFORE STEP 1, UNPLUG ALL WINDOWS DRIVES, AND RECONNECT AT THE END OF ALL STEPS**
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STEP 1 (ALTERNATIVELY, FOLLOW nullspot's USB INSTALLATION GUIDE FOUND AT END OF THIS POST TO INSTALL SL TO THE HDD- I WILL INTEGRATE IT INTO THE MAIN GUIDE SOON.)
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Start by booting into your existing OS X installation and firing up Disk Utility. Select the disk you intend to install SL to, and click on the "Partition" tab. Change the "Volume Scheme" drop down menu to "1 Partition", and then click "Options...". Select GUID, and click ok. Before you Apply the changes, give your drive a name, preferably something easy to remember, I named mine Snow.*

*If you want to install to an MBR partiton/drive, then you can try this, but I haven't tested it personally:

QUOTE (knew know @ Aug 29 2009, 05:13 PM)

I mounted the SL dmg file (I didn't use the DVD, I used an image) and opened disk utility to convert the image to "read and write". Click on Convert at the top of disk utility with the dmg selected. It will prompt you to save the converted .dmg somewhere on your drive. Do so....unmount the readonly dmg of SL and mount the newly created one. Then navigate to "/Volumes/Mac OS X Install DVD/System/Installation/Packages", delete "OSInstall.mpkg", add the one on this page http://limiter.fre3.com/blog/?p=19 and follow the rest of d00m's awesome tutorial ;P.

This one will allow you to install on mbr ;P. Hope this helps ...

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STEP 2
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Next, insert your Snow Leopard DVD and navigate to the root of the DVD. Under the menu, click Go, then select Go to Folder. Paste this: "/Volumes/Mac OS X Install DVD/System/Installation/Packages" without quotes into the box, and hit enter. You should see a number of packages. Find OSInstall.mpkg and run it. Select the drive you intend to install SL to, I'll call it Snow.*

*Note: My first issue occurred here, where I got an "Install Failed" message after the installation completed. If this happens to you, try deselecting the Printer Drivers and Languages under the "Customize" menu during the install. It should succeed then.

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STEP 3
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Do NOT reboot yet, first we have to install a bootloader, as well as a few important kexts and other files. Start by running the PC EFI 10.1 package, and selecting the Snow drive. (This version of PC EFI 10.1 is already fixed for SL, no need to replace any boot files) Next, open the Extra folder in my pack, and copy its contents into the folder on your Snow drive also labeled "Extra". We will have to edit a bunch of these files, do don't use them as they are, as they are configured for MY machine which is most likely different from yours. Keep in mind I have a GA EP45-UD3R, so if you have an L or a P, then you might need to adjust your kexts and files slightly after some research.*

*Remember, if you do NOT use any IDE devices, then delete JMicronATA.kext, it is not needed. If you DO on the other hand, then keep it as you will face various issues/KPs without it. Also remember this:

QUOTE (richtig @ Aug 28 2009, 11:51 PM)

A JMicron controller driver may also be needed, if intending to use the 2 purple SATA ports. The IDE port & the 2 purple SATA ports both run off the same JMicron chip. Commonly used for providing eSATA functionality.

*Also one thing to bring up, if you have an EP45-UD3L, then you have a different audio chipset:

QUOTE (ximekon @ Aug 29 2009, 07:47 PM)

Anyway one thing: according to this site: http://www.incomplete-news.com/?p=2512
the EP45-UD3 L uses the ALC888 chipset. Yours the UD3R has ALC889a chipset.

So if you have an L, then you will need to use a different LegacyHDA if you want System Profiler to show the correct information. Otherwise, functionality will be the same if you patch your DSDT for the alc888 and use SL's default AppleHDA.kext. There is a guide on the forum I will look for the URL of, which details sound on these boards much more in depth.

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STEP 4
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First thing we have to take care of is manually editing the UUID of the Snow drive into two different locations. First, open the "smbios.plist" (from your Extra folder) in TextEdit. 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.

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STEP 5
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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 TextEdit. Copy your UUID again, and paste it over where it says "PASTE YOUR UUID HERE". Save the changes, and close the window.

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STEP 6
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Next, open up EFIStudio, located in the root of my Pack folder. 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 TextEdit), and paste that long hex string you copied over the long hex string already there (mine). Save the file, and close the window.

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STEP 7
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Finally, you have to compile your own edited DSDT.aml to get working ethernet/sound. You will see there is already a DSDT.aml in your Snow Extra folder (the one you copied from my pack). You can try using this, but it will most likely not work as a DSDT depends on quite a few things specific to your machine. your best bet is to delete it, and open the DSDT Stuff folder in my pack, following the instructions in the "How to Patch DSDT" folder, labeled "How to patch DSDT with LAN and HDEF functions.pdf". This is NOT my guide, so I take zero credit for writing it. I am only providing it here for you conveniently so you do not have to go out and search for it. When I make a later edit to this guide probably by next weekend, I will give credit to the author/poster of the guide, although the original information on editing DSDT was posted by Taruga and THe KiNG. Make sure you apply the CMOS reset fix to your DSDT, as Snow Leopard has a nasty bug that will reset your CMOS every time you boot it up otherwise.

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STEP 8
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Once you have your compiled/edited DSDT.aml, drop it into the "Extra" folder on your Snow drive (where you deleted the original one from).

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STEP 9
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REBOOT! Make sure you are booting from your Snow drive, and it is IMPORTANT to boot with the -v -x32 flags on first boot. At this point, you should pay attention to the verbose output, and if you run into any kernel panics or endless loops, post the output here for troubleshooting. (Also keep in mind this guide was designed for specific motherboard(s), so there may be some unexpected results for a different mobo)

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STEP 10
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If all goes well, you should see the whole "Welcome" flying through space intro for SL. It SHOULD have sound, graphics, and ethernet working at this point, but if you don't hear anything don't be alarmed. After running through setup (when you arrive at the desktop), quickly open System Preferences, click on Spotlight, and click on the "Privacy" tab. At the bottom, click on the + sign, and add every drive/storage device to this list (this is only temporary, to avert a kernel panic caused by a Spotlight indexing service, mdworker).*

Alternatively, you can just make the drives "Private" using Leopard as Elaide figured out:



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STEP 11
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Rebuild your kextcache using the included Kext Utility (if this doesn't work you could always use terminal and do it manually, but it almost always works fine), and restart. When you boot, boot with -v -x32 again, and make sure there are no issues. When you get to the desktop this time, go back to Spotlight preferences, and remove all of the drives from the Privacy list with the - sign. Click on the menu bar Spotlight icon in the top right corner, and type something into the box. It should start to index your drives. If you rebuilt the kextcache correctly, it should have zero problems. Let it complete the index process.
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STEP 12
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Finally, in the meantime, you can open System Profiler from the Utilities folder and check to see if your graphics card is fully supported (you should have all of the resolutions native to your monitor if it is anyway), and also check on the sound/ethernet. If your sound is working you will obviously know, as the little clicks sound when you change the volume, and under System Profiler you will see details about the audio device- an alc889a. Finally, go to System Preferences>Network, and check the status of your ethernet connection. If it's "Connected" without a Self-Assigned IP (and you USE wired ethernet), it should be working, just open a Safari window to test this.

Enjoy your SL installation, and be sure to test if sleep works after you have everything else working, as it should work fine.

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Troubleshooting
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1. If you get a KP related to mds or mdworker, it has to do with the Spotlight indexing problem. Solution - rebuild your kextcache in Single User Mode, or boot into SL and quickly disable Spotlight's indexing by adding all of your storage devices to the "Private" list in System Preferences>Spotlight.

2. If your sound/ethernet doesn't work, it's probably the DSDT. Solution - "If at first you don't succeed, try, try again." DSDT is a pain in the ass, and the only way you're going to get it working right is with a few mistakes along the way. You can try mine, but you NEED an Intel C2D processor and a GA EP45-UD3R mobo to have it work at all.

3. If your graphics don't work, it's probably the EFI string you put into com.apple.Boot.plist. Solution - make sure you used the right string, and always do a little searching to make sure your card is supported well with a string. I know more about Nvidia cards than ATI ones, so the ATI folks will have to probably do more searching before they come to me with an issue because I might not be able to answer it well.

4. KP due to Software Update. Solution - I have no idea yet! I'm looking into this, but I do not have this problem yet, so if anyone does have this as well, post your configuration in detail including hardware/kexts so I can try to isolate the issue. ***UPDATE*** Possible solution includes making sure you rebuild your kextcache after everything, BE 100% SURE IT WORKED!

5. Bonjour doesn't work (this will always happen). You can either ONLY boot in 32-bit mode and use Realtek1000.kext, or use this simple fix posted by Eliade which works in 32 and 64 bit! (All of the files mentioned in this guide are in the /Extra/Bonjour folder)



6. This is a huge find, and I thank BillaBongo for pointing this out, because even though I did this unintentionally, it could be the cause of many problems. UNPLUG YOUR WINDOWS DRIVE(S) PRIOR TO FOLLOWING THIS GUIDE!


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MORE ISSUES TO COME AS THEY ARRIVE.
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P.S. Feel free to post any issues/KPs here, but make sure you have a log to post or a picture of the KP so you aren't just saying, "OMGZORZ MAH COMP FROZE WIT BLACK N WITEE TEXT!!!", because frankly, that doesn't do me much in understanding what caused it lol >.< Also, if I'm missing anything that you think should be added or edited in, tell me

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nullspot's USB Installation Guide (to be integrated soon):