Assassin's Creed Syndicate PC is now available on Steam. Meanwhile the PC and a day-1 update is currently available for it.
According to the release notes, this patch improves multi-GPU functionality and improves PCSS and HBAO+ render quality.
Assassin's Creed: Syndicate - Patch 1.12 Changelog:
Improved Multi-GPU functionality
Improved PCSS and HBAO+ render quality
Added VRAM Meter in Video Options
Added HBAO+ Ultra parameter in Graphic Options
Fixed various window mode issues
Fixed Alt+Tab issue in Fullscreen mode
Fixed issues on switching displays in Fullscreen
Fixed various render issues
Fixed various UI issues
Fixed various online issues
This patch will be auto-downloaded from UPLAY or Steam.