Download and Install CM10 Preview ROM For AT&T, T-Mobile or Sprint Galaxy S3

Rooting your Galaxy S3 (Tutorial how to root Samsung Galaxy S3) means obtaining “superuser” rights and permissions to your Android’s software. Once Galaxy S3 gets rooted, you gain the ability to load custom software or ROM, install custom themes, increase performance, increase battery life, and the ability to install software.

What is Cynaogen Mode ROM?

You can refer here (Video) for more info.

The Cyanogen Mod is one of the most popular mods currently out for Android. It allows you to customize your device how you want to and adds features that are not in the stock Android experience such as incognito browsing and lock screen gestures. Of course, when you say developer community, the first name that comes to mind is CyanogenMod. The CM team is already hard at work preparing the new CM10 (CyanogenMod’s version of Android 4.1 Jelly Bean) . The team behind the famed firmware has been slaving away on its latest development – CyanogenMod 10. Keep in mind, of course, that CM10 still in the testing stage and the  “preview build” translates into “absolutely nothing is guaranteed to work.”

Known issues being worked on CyanogenMod 10 Preview Builds for SPH-L710:
* Overlay for UI (extra butter)- We’re waiting on CodeAurora to publish, UI is a little janky.
* Camera preview turns green during animations and may crash.
* MMS downloading doesn’t work but sending & retrieving does work, use a 3rd party SMS/MMS app that can download them.
* All the things.
Download: Link
Developer source: Link
Known issues being worked on CyanogenMod 10 Preview Builds for SGH-T999:
* Overlay for UI (extra butter)- We’re waiting on CodeAurora to publish, UI is a little janky.
* Camera preview turns green during animations and may crash.
* Audio may crap out completely after a call
* All the things.
Download: Link
Developer source: : Link
Known issues being worked on CyanogenMod 10 Preview Builds for SGH-I747:
* Overlay for UI (extra butter)- We’re waiting on CodeAurora to publish, UI is a little janky.
* Camera preview turns green during animations and may crash.
* Audio sometimes dies completely
* All the things.

Download: Link
Developer source: : Link
Here is the Tutorial on How to install CyanogenMod 10 Preview for SGH-I747, SGH-T999, SPH-L710
Your phones must have rooted access and Installed CWM Recovery. Here is the Tutorial how to.
Step 1:Copy and paste the downloaded “CynogenMod10 Preview (zip File)”  and “gapps-ics-20120429-signed.zip”  into Galaxy S3 external SD card storage.
CynogenMod10 Preview (zip File) mean:

CyanogenMod 10 Preview Builds for SGH-I747: cm-10-20120717-Unofficial-d2att.zip
CyanogenMod 10 Preview Builds for SGH-T999: cm-10-20120716-Unofficial-d2tmo.zip
CyanogenMod 10 Preview Builds for SPH-L710: cm-10-20120716-UNOFFICIAL-d2spr.zip

Step 2:Power Off your Galaxy S3.
Step 3: Press Volume Up + Home Button + Power Button until your Phones boot into CWM Recovery Mode. ( This step is almost same to boot your S3 into Downloading Mode, refer here for more info)
Step 4: Select wipe data/factory reset, then select Yes. (Note: this step will delete your Galaxy S3 data, so you can refer hereon how to backup Galaxy S3 data).
Step 5:Press volume down until option “Install Zip From SdCard”, then press Power button to select “Install Zip From SdCard” .
Step 6:Now chose “ Choose zip from SDCard”
Step 7:Press volume down and then Power button to choose  “CynogenMod10 Preview (zip File)”
Step 8:Press volume down and then Power button to choose “Yes- CynogenMod10 Preview (zip File)”
Step 9:Now is the process install  “CynogenMod10 Preview (zip File)” .
Step 10:Now install Google Apps. Press volume down until option “Install Zip From SdCard”, then press Power button to select “Install Zip From SdCard” . Now chose “ Choose zip from SDCard”. Press volume down and then Power button to choose “gapps-ics-20120429-signed.zip”. Press volume down and then Power button to choose “Yes-install gapps-ics-20120429-signed.zip”.
Reboot your S3 after installation complete. That’s All!