4k monitor only works at 30 hz on start up

[Rom Hook]

I've recently bought a 4k LG 27UD68 monitor and when I start my computer I get "The system has detected a link failure and cannot set the requested resolution and refresh rate. Your display might not support the requested resolution or there may be an issue with the cable connecting the display to your computer" error when connecting it through DisplayPort cable. To fix the issue I have to unplug and replug the monitor from the power outlet. Fortunately this monitor came with HDMI cable as well, and it seam to work fine when using HDMI port. Do I lose any functionality when using HDMI? Would buying a different display port cable solve the issue?
Thanks!

 

[gillhooley]

What video card are you using? It may only support 4k at 30hz, especially over HDMI.

 

[Rom Hook]

It's a Power Color rx480 red devil 8GB with the latest drivers. I've had the same issue with the old drivers as well.

 

[Uruquel]

Seems that you need to conect it to display port

 

[gillhooley]

That model has HDMI 2.0 so it should work either way, is the HDMI you are using HDMI 2.0 compatible? You should try a new Displayport cable it is a cheap fix, if it works

 

[Rom Hook]

It's HDMI 2.0 compatible. I might be wrong but there seam to be a little bit of screen tearing when using HDMI even with AMD freesync turned on.