https://wccftech.com/msi-brings-resizable-bar-amd-smart-access-memory-support-to-hedt-platform/

Resizable-BAR (AMD Smart Access Memory) support has so far been exclusive to mainstream AMD & Intel platforms but it looks like MSI has finally brought the feature to the HEDT platform. MSI has announced new BIOS for its entire AMD TRX40 board lineup which now supports the resizable-bar feature with the Ryzen Threadripper CPUs.

As per MSI, they have now listed the latest BETA BIOS on the support page for all four of their AMD TRX40 chipset based motherboards. The main update within the BIOS is support for the resizable-BAR function which "enhances GPU performance including AMD Radeon RX 6000 series & NVIDIA RTX 30 series".