The v1.1.640 patch is the final official update released by Maxis/EA. It addresses two major categories of issues:
Reliable community hubs like Simtropolis and SC4Devotion are the safest places to find these legacy patch links. These sites have archived the official Maxis updates that are no longer hosted on Electronic Arts' main servers. Avoid third-party "abandonware" sites or suspicious file-sharing links, as these can contain malware or corrupted files that will break your installation. simcity 4 deluxe edition v11640 patch link