NVIDIA NVFlash with Board Id Mismatch Disabled v5.541.0
2.6 MBWin 10, 8, 7 (64-bit)nvflash64_patched_5.541.0.zip77949264905745F6637702B582A98396
This is a patched version of NVIDIA's NVFlash.
On Turing cards, NVFlash no longer allows overriding of the "board ID mismatch" message through command-line parameters, so flashing the RTX Founders Edition cards with a custom-design BIOS isn't possible anymore.
Vipeax has thus modified the official NVFlash binary to bypass this error. You don't have to supply any additional parameters to bypass the board ID check.