Weird issues with optical DisplayPort on 3080 Ti

Ulrar · August 15, 2022

Hi,

Built a new PC the other day with a Gigabyte Z690 Gaming X (DDR5), an Intel 12600k and a Samsung 980 pro in the M.2 A Slot (CPU). I've racked it next to my server in another room, so it's connected to my monitor using a 20 meters optical DisplayPort 1.4 cable -> DisplayPort to Mini Display Port keystone jack in the wall -> Mini DisplayPort to DisplayPort 5 meter normal cable -> Monitor, and an active usb 3.0 cable (non optical). It's been stable, and able to go to to 60 Hz at 1440p without issues for the past week or so.

Today I've received a 3080 Ti, which I've slotted into the PCI-E 16x slot and plugged in the extra power connectors.

It's detected fine by both the bios and Windows, at gen 4 speed.

My issue is the optical Display Port only works at 24 hz, anything above that just goes no signal.

I've also noticed that even at 24 hz it won't come up unless something else is also connected, either hdmi or DisplayPort, doesn't need to be the same device. But if the optical DP is the only thing connected then it doesn't come up at all, which makes no sense.

I've tried connecting a monitor directly using a short non optical cable and it works fine, so presumably the optical cable is the issue, but I don't understand why the motherboard / igpu is capable of using it perfectly fine but the GPU isn't. I've disabled G-Sync to make sure and no difference.

Any idea on what might be going on, and what I can do ?

Ulrar · August 15, 2022

Quick update, did some more testing with more monitors and it seems the issue is only with my AOC AG271QG, I have two other LG monitors that are working perfectly fine at any resolution and refresh rate, including 4k.

That's unfortunate because the AOC is the only one with >60hz refresh rate and gsync, but at least I can play on my work LG for now.

If anyone has an idea on why my AOC and my RTX 3080 Ti don't like each other, I'd love to solve that !