https://wccftech.com/asus-lacking-behind-other-manufacturers-in-resizable-bar-support-for-intel-z390-z370-motherboards/

ASUS is once again lacking severely behind other manufacturers when it comes to offering support on its older generation of motherboards. Last year, ASUS missed the PCIe Gen 4.0 train on its Z490 lineup, & this year, the company has failed to provide any support for Resizable BAR on its Z390 & Z370 lineup of Intel motherboards.

Over the last couple of months, each major manufacturer, excluding ASUS, has been releasing its BETA BIOS which adds in support for Resizable BAR on older Intel 300-series motherboards. BIOS updates for the Z390 and Z370 lineup of motherboards were released by MSI, ASRock & Gigabyte but ASUS has yet to do the same.