It’s raining CyanogenMod 11 ROMs and most of the top devices with active developers are getting unofficial builds of CyanogenMod 11 that are built upon Android 4.4 sources. These ROMs are updated as and when CyanogenMod team pushes code to its github. temasek on XDA Developer forums has compiled the CyanogenMod 11 ROM for Samsung Galaxy S3, although we are pretty sure that the CM team will develop a CM 11 ROM for the S3 soon. Before that you can go ahead and taste Android 4.4 on your SGS3.
While you go ahead and install the ROM, make sure you have a backup of your data before you proceed. You can refer our backup guide or create a Nandroid backup using OBackup. After you are done with the installation, you can restore data using Nandroid Manager.
Disclaimer: Hack My Android is not responsible for any damage your device might incur during this process. Proceed at your own risk.
To install the ROM, all you need to do is download the ROM and Gapps zip file from the original thread link at the end of this post and place it in your device’s storage. Make sure your device has the latest CWM installed. You can use ROM Manager to check that. After you have made the backups, you can boot into CWM and flash both the ROM zip file followed by Gapps zip file. After you reboot your phone, you should be good to go with the CM 11 ROM on your Galaxy S3.
For issues and downloads, make sure you check out the original thread.