Rise of the Tomb Raider was updated today to version 1.0.638.6, which is a bigger deal than its less-than-snappy name suggests. In DirectX 12 mode Multi-GPU support is now available.

The update adds support for DirectX 12, which “on the right hardware can offer far better performance” than was previously achievable, as well as for Nvidia's VXAO ambient occlusion technology, described by Square Enix as "the world's most advanced real-time AO solution."

• Adds DirectX12 Multi-GPU support. Many of you have requested this, so DirectX 12 now supports NVIDIA SLI and AMD CrossFireX configurations.
• The benefits of DirectX 12 are still the same, but now you are less likely to be GPU bottlenecked and can reach higher framerates due to the improved CPU utilization DirectX 12 offers.
• Adds utilization of DirectX 12 Asynchronous Compute, on AMD GCN 1.1 GPUs and NVIDIA Pascal-based GPUs, for improved GPU performance.
• On the latest Windows 10 version, V-sync can now be disabled (Windows Store version), and behavior of disabled V-sync has been improved (Steam version).
• Improvements to stereoscopic 3D rendering, including fixes for NIVIDA Surround and AMD Eyefinity in combination with stereoscopic 3D.
• Improved default settings for certain integrated GPUs.
• Removes the Voidhammer Shotgun for users that do not have Cold Darkness Awakens DLC or have not yet unlocked it by rescuing prisoners in Cold Darkness Awakens.
• A fix for a save issue where some game state could get lost in very rare circumstances.
• This patch force-disables the Steam Overlay when using DirectX 12. This is due to stability issues with the Steam Overlay in combination with DirectX 12.
• A fix for crashes with VXAO enabled on NVIDIA GTX1080 cards.
• A variety of other smaller optimizations, bug-fixes, and tweaks.