I've installed another GPU card RTX 2070 in the second PCIex16 motherboard slot. Not a SLI connection. Both cards were previously installed in this machine separately with the drivers updated for both. Blender doesn't want to open. A video card and driver with support for OpenGL 3.3 or higher required. Why am I getting this message? TY.
Here is how I made it work. I had to flash the bios. If you are like me playing with the settings all the time you need to reset the bios by taking out the little round battery on the mobo. Depending on your mobo, the flash reset button next to the usb slots on the mobo didn't work for me, it might work for you. After that blender will open and both cards are seen in Cuda and Optix. Indeed there is some work but I'm pretty happy with the result right now. However render time is not cut in half though. More like 35% less with two cards.