It varies from mobo to mobo. Typically F8, F12, or Delete. It will say on the splash screen when you boot up, but it might be quick depending on your hardware.
That makes no sense, I’ve got the same processor running at a slower speed, with a 1050ti OC, I don’t get why you are having issues. It must be something with your PC, because mine runs it at ultra at 40-60 fps.