NvStrapsReBar, a new UEFI driver that enables Resizable BAR support on NVIDIA’s Turing GPUs (i.e., the GTX 16 and RTX 20 Series), is now available for download, per terminatorul’s GitHub page. A list of motherboard/GPU combinations that are confirmed to be working, including the ASRockX99 Taichi and GIGABYTE GeForce GTX 1660 SUPER OC 6G, have been listed here.
Instructions, per terminatorul:
- update the motherbord UEFI image to add the new NvStrapsReBar.ffs driver (see below)
- enable ReBAR in UEFI Setup if the motherboard supports it. Otherwise enable “Above 4G Decoding” and disable CSM
- run NvStrapsReBar.exe as Administrator to enable the new BAR size, by following the text-mode menus. If you have a recent motherboard, you only need to input E to Enable ReBAR for Turing GPUs, then input S to save the new driver configuration to EFI variable. For older motherboards without ReBAR, you also need to input P and set BAR size on the PCI side (motherboard side).
- reboot after saving the menu options.
- for older motherboards without ReBAR, if you want to load default UEFI settings again, or disable Above 4G Decoding / enable CSM, you need to disable ReBAR first in NvStrapsReBar.exe. Or you can manually set back the current year in UEFI Setup.
- same issue if you make hardware changes like adding or changing a GPU: you have to disable ReBAR first. The reason is NvStrapsReBar depends on the GPU BAR0 address to enable ReBAR, and system firmware changes the allocated address for BAR0 when hardware is changed or settings in UEFI Setup are changed.
A note about the motherboard flashing requirement:
It’s ususally the video BIOS (vBIOS) that should enable ReBAR, but the vBIOS is digitally signed (NVIDIA vBIOS is also encrypted) and can not be modified by modders and end-users (is locked-down). The motherboard UEFI image can also be signed or have integrity checks, but in general it is thankfully not as locked down, and users and UEFI modders often still have a way to modify it.