1) Give us more details: What's your rig, which OS you are running
2) Have you tried to simply remove or re-install NVidia drivers?
3) Have you tried re-configuring xorg manually or at least running nvidia-xconfig
i tried 6 xconfigs. for prime on 440, but nvidia disabled them in driver 440, but somehow works xconfig less. in prime you also cannot use "nvidia-settings coolbits=number" or whatever that command is. to ensble on 16.04 i need to edit the file as admin and reboot.
418 i can overclock like a charm with the working configs of gpu.
mobo: Z390 taichi ultimate
storage/os/drivers: 860 evo sata 1tb ubuntu 16.04 nvidia driver 418
corsair mp500 nvme 120gb umix 20.04/ driver 440.
gpus: pci slot main: p102-100 2nd slot: p104-100
psu: corsair rm750
other info: both drivers work with 2 p104-100's in, the p102 alone, the p104 then p102 in second slot, but it gives untrudted key when the p102 is in primary with p104 in second slot. i only need the p104 to act as an nvenc encoder as in a prime setup, that codec doesn't work unless 2 cards are in pc.
i change gpu configs alot, or had to before i got the p102, and i can't change the driver with the p102 alone, it simply just works. so i figured having the p104 in would kill 2 birds with 1 stone. i get to try nvenc, and access the driver change button without physically swapping gpus.
so, how do i remove the untrusted key error? i can access both grubs. is there a way to sign them myself or tell it to ignore the error like it does the apci? is it as simple as disabling secure boot? it may be off, unsure.