Which slot do you install in one graphics card only and it is working fine?
Do you mean you have tried both of them on PCIEX16_1, PCIEX16_2, PCIEX16_3, and each of them are working fine?
Do you enable crossfire or openGL?
If you install two graphics card meanwhile, is it black screen at first or after booting windows or after running apps for a while?
Have you restored bios to all default settings but it is still black screen?
If yes, please also update to the latest bios version 2004.
Using any M2 devices?
your CPU supports 16 lanes. 2 GPUs at X8 and you are done. I ran two 1080 Tis on the same board with a 7700K but nothing else using the lanes and they had to be set to X8.
Did you install both graphics card in PCIEX16_1 and PCIEX16_3, so you haven't tried PCIEX16_2?
Please also try PCIEX16_1 and PCIEX16_2.
If it is still black screen, please restore bios to all default settings and update to the latest bios version 2004.
Do you have other graphics card?
Is the screen still black with bios all default settings on bios version 2004?
Please reinstall Icue for your fans.
May I have the specific model name of the ram such as F4-3000C16Q-32GTRG?