If it's already plugged then the second option is not needed since it's known that your nvidia gpu is the main graphics processor. Can you share pictures of your system info? for example screenshots of games with fps and gpu usage in the corner and pictures inside NVIDIA control panel and...
Make sure you plugged your monitor to your graphics card not to the motherboard.
Go to NVIDIA control panel →Manage 3D settings→Global settings→Preferred graphics processor and choose High performance Nvidia processor.
Try resetting the bios by removing the CMOS battery and unplugging the pc from socket for few seconds to minutes, if that didn't work try booting with only one stick of ram, yes I know what does ram have to do with this but sometimes it works. good luck.
The monitor and keyboard are separate components i.e. they consume electricity from different sources. I'd recommend checking the following:
If you're using a power strip to power for your pc and monitor try a different one and preferably with a wall socket you know is working well.
If it's not...
I add my dualshock 4 in bluetooth, it pairs and connects perfectly well, but after I disconnect the controller by holding the ps button, and then turning the controller on again it does not connect automatically, instead I have to remove the controller then re-add it which of course shouldn't...