Mojave thinks its displaying to my primary monitor, but it's displaying to my secondary monitor

Resubmitting because I can't make titles properly

This one has got me stumped. I have macOS Mojave fully installed and everything seems to be working, except for the display. In order to be able to see the actual GUI after the verbose boot, I need to have a DVI cable connected from the motherboard to my primary monitor, and an HDMI cable connected from my motherboard to my secondary monitor. In this configuration, I get fully working video output on my secondary monitor. This is the ONLY configuration that allows me to get video output. Removing either cable causes the video output to go away. In macOS itself, the display is being recognized as my main display by name (in About This Mac under Displays it lists the model of my primary monitor) so it seems to think that it's outputting to my primary monitor when it's actually outputting to the secondary monitor. I've followed the IOReg stuff in the vanilla guide to fix the device ID from DisplayPort to DVI but it's still outputting over HDMI. In fact, regardless of what I change the framebuffer stuff for the con type to, it still outputs over HDMI to the secondary monitor. Someone suggested unplugging the monitors for more than a minute but that didn't have any effect either. Anyone got any ideas?