PC Drivers & Software

[szpeter]

I have a 4k@120hz monitor as my main monitor and another 2k@60hz as my secondary monitor.

I found out that as soon as I plug the secondary monitor in, my 4k@120hz monitor dropped to 4k@60hz, and there is no longer 120hz option in the windows resolution settings nor in the Radeon co...

4K@120 hz only

after that second monitor plugged in, the bandwidth dropped and 120hz gone

[itech8]

Hello szpeter, I have the exact same situation. I have a SAPPHIRE Radeon Pulse RX 580. Did you find the reason why the main monitor drops the hz?

[szpeter]

See my comment below

[elstaci]

Go to Windows Settings - Display.

Click on your 4k@120hz Monitor and make it your Main Display and then Chose to "Duplicate Desktop 1 & 2"

Now go back to your 4k @ 120hz Monitor and see if it is now available in Windows Settings. IF it is then click on the 4k @ 120 hz selection.

If you have it set to "Extend Desktop to 1 & 2" it will probably force both Monitors to run at its lowest Maximum Hz.  I am just guessing due to my experience when I connected my TV set to my PC Monitor through my GPU Card.

I notice this when I connected my 2k@60hz Samsung TV to my 4k@60Hz Monitor. My 4k Monitor automatically resolution went to 2k the same as my TV. But the 4k Resolution was available though in Windows Settings and I was able to reset it to 4k after changing to "Duplicate Desktop to 1 & 2".

Also in Windows Settings see if the 120hz Frequency is listed under Display:

If none of the above works try using a tiny Monitor Program called Custom Resolution Utility (CRU) where you can add the correct frequency to your Monitor. 

But make sure you read the instructions on how to use that program since I believe it changes the EDID of the Monitor.

[szpeter]

No, it's not available in windows' setting. It's like as if the card is simply not able to push out that many pixels. I tried connecting two display port to my 4K 120hz monitor (so it should not have a monitor bottle-necking the other at a lower refresh rate), but 120hz is simply gone. At this point I think we need AMD engineer to confirm this limitation.

[elstaci]

See what version of HDMI and DP does your RX 580 GPU Card outputs has?

Those versions will tell you the Maximum Resolutions and Frequencies your GPU card will support.

[szpeter]

It's XFX RX580 black edition, so from techpowerup.com, it should have:

1x DVI
1x HDMI 2.0b
3x DisplayPort 1.4a (this would definitely support 4K @120hz no problem)

And the problem isn't even related to ports, because it's the same monitor plugging into the same port before and after. The 4K 120hz option just disappear after pluging in a second monitor (and it will re-appear if I remove that second monitor). This suggest there is bug in the driver or some arbitrary limitation to the card

[elstaci]

The DVI port doesn't support 4k@120hz but the HDMI and DP ports should support 4k@120hz.

I been seeing some threads recently concerning the same issue of not supporting 120hz Monitor.

Anyways, I suggest you open a AMD SUPPORT Ticket and see what they say from here: https://www.amd.com/en/forms/contact-us/support.html

If you do get a reply please post it here to your thread in case it might be useful information to other Users.

@itech8  mentioned something about the monitors but I couldn't find out which Monitor Models you have for our 4k and 2k Monitors so I don't know if he is talking about your Monitor models or not.

[itech8]

Hello Friends, 

I received response from the monitor manufacturer (KTC-Gaming Support Team). They recommend the AMD card 6800 or above for two 4k monitors at 120hz. It was not a detailed answer but I assume the RX580 Its not going to work.