No video out when a graphics card is installed

[Usernaym]

I recently completed my first scratch build after years of messing with used prebuilts, and I'm having some issues. I'm running Ubuntu 20.04 64 bit, having carried over the boot drive from my previous system, which I suspect may be causing some driver issues. Without a graphics card installed the system works almost perfectly, booting into the OS no problem, but as soon as one is in the slot, the pc still boots, but without any display output. Occasionally, the BIOS will display from the GPU, but at a weird resolution and at roughly half the area of the monitor. Even if that comes up, it will not display after exiting the BIOS. My important specs are as follows:

CPU - Core i7-4790K

RAM - 2x8gb G.Skill Trident X 2400mhz

Motherboard - Asus Z87-K (BIOS version 1402, most recent)

GPU - EVGA GTX 680+ 4gb

PSU - Corsair CX600

Normally I would swap in a Windows drive at this point to see if it would behave, but I'm stuck in quarantine without access to any backup hardware, so I'm a bit stuck. Other potentially relevant information:

-I'm using DVI for my display, and my monitor does not have any displayport or HDMI ports to test with.

-XMP doesn't seem to stay on, though that may be down to me being new to this BIOS and still learning.

[Fasauceome]

what happens if you use the other PCIe slot for the graphics card?

[IkeaGnome]

Have you installed drivers for your GPU?

[Usernaym]

2 minutes ago, Fasauceome said:

what happens if you use the other PCIe slot for the graphics card?

I have the same issue regardless of which slot the card is in unfortunately

[Usernaym]

3 minutes ago, IkeaGnome said:

Have you installed drivers for your GPU?

I thought I had, but when I checked, it looked like it wasn't actually installed. Let me try that again.

[Kilrah]

When you're installing your GPU you connect the display to it, right? 

When a GPU is in the internal graphics will get disabled so the mobo port goes dead.

[Usernaym]

2 minutes ago, Kilrah said:

When you're installing your GPU you connect the display to it, right? 

When a GPU is in the internal graphics will get disabled so the mobo port goes dead.

Yes, I've been moving the cable to the DVI out on the GPU. Thanks for checking, though

[Usernaym]

okay, I installed the driver through the terminal, no luck. Rebooted a couple of times and still nothing.

[Usernaym]

Alright, I finally got it to display through the 680, but it's using the X.Org X server open source driver, which I'm guessing will have worse performance in games than the Nvidia proprietary one, but it wouldn't display at all with the supposedly correct proprietary driver, so I'm hesitant to mess around too much.