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Journeyman III

Dual Monitors 2 Graphics Cards - Help Requested


I have a middle-aged system - Gigabyte GA-X79-UP4 mobo, Win 10 x64, 2x Catleap Q270 monitors @ 2560x1440. For some time I have installed 1x RX480 and 1x HD7800 graphics cards with DVI-D Dual Link connection separately to each monitor - all running fine and well. DVI-D Dual Link is the only connection available on the Catleaps

I thought to get another RX480 to provide a balanced colour rendering (the HD7800 is a little 'creamy'). However, after swapping the HD7800 for an RX480 there was no signal to the 2nd monitor. Two display adapters showed up in Device Manager but not in Radeon settings or Windows Display Settings.

I have tried various combinations of HDMI and DisplayPort to DVI-D Dual Link (incl an expensive Active DP adapter) with no success.

There was even no signal when I tried to run the 2nd monitor off the one RX480 via DP or HDMI - this combo showed up in Radeon settings but not Windows Display Settings.

All Radeon and Windows drivers are up to date as of April 7th 2019

So my conundrum is that the 2-card RX480/HD7800 setup works fine but I cannot get RX490/RX480 to work. Any help or advice would be gratefully received. Thank you


5 Replies
Big Boss

use DDU to clean driver
reinstall driver 19.4.1 (very good driver)

have in mind that RX480 does not have an active DVI

PC: R7 2700X @PBO + RX 580 4G (1500MHz/2000MHz CL16) + 32G DDR4-3200CL14 + 144hz 1ms FS P + 75hz 1ms FS
Laptop: R5 2500U @30W + RX 560X (1400MHz/1500MHz) + 16G DDR4-2400CL16 + 120Hz 3ms FS

Thank you – that has worked!

I had to uninstall the adapter in Device Manager for it to show but hey presto! looking good

I appreciate your help and advice



Bug Driver : Second Monitor only after Reboot


Well, curiouser and curiouser. Spoke too soon.

I do now have a functioning 2nd monitor which shows up only when I uninstall the adapter in Device Manager (every reboot it seems).

However it shows up in Windows Display Settings as connected to ‘Microsoft Basic Display Adapter’ and it also does not now show in Radeon settings.

Any further thoughts appreciated



Only connect primary monitor to primary GPU display output when you install the AMD driver. Once you install the driver check to see if Crossfire is on in AMD Settings for the Primary GPU. Turn Crossfire off. Power down the PC. Connect the second monitor to the second GPU. Boot up. Check that Crossfire is off. See if your displays work.
Hope that helps you solve this one.