Question No signal mystery with multiple monitors and video cards

Dec 28, 2020

I have an issue with my computer (which has worked fine for 4 years) suddenly not giving any signal to the monitor when a video card is installed.

When the video card is installed, the system boots and everything turns on (I can see the fans spinning on the CPU and GPU) but the monitor displays no signal. It does not matter what monitor I use, or if I try and plug the hdmi into the motherboard rather than the video card. However if I physically remove the video card and plug the hdmi into the motherboard, I can run on the integrated graphics.

I concluded that the video card was broken and replaced it (and the drivers). This actually fixed the problem for a few days but then infuriatingly the issue re-emerged and once again I cannot run my computer except by removing the video card. I am entirely a loss at what the problem could be?

First video card: Sapphire R9 380 Nitro
Second video card: ASUS Radeon RX 5500 XT DUAL EVO OC