My screen turns off when I play on my computer.

Hello everyone, I hope you are doing well. I am new to the platform and I would like some help with an issue that has been bothering me for about ten days.

I have a PC running Windows 10 with a Radeon RX 580 series graphics card and an Intel Core i7-6700K CPU 4.00GHz.

Let me explain:
I have 2 monitors, and when I launch the video game Fortnite, after about 20 minutes both of my screens go black, I hear a USB cable disconnection sound once, my audio cuts out for 15 seconds, then my screens go into sleep mode (their blue LEDs turn orange), the sound returns (Discord still works), but nothing helps; I have to restart my PC to see it again (I restart it as safely as possible by pressing Windows + D and Alt + F4 in a loop instead of directly pressing the tower).

Once turned back on, I do have 2 screens again, but they display the same thing. I've searched for multiple solutions, and I found one here that was effective but only short-term:
https://forums.commentcamarche.net/forum/affich-35372647-votre-pc-ne-peut-pas-utiliser-un-autre-ecran

The problem was similar since when pressing Windows + P,

this message also appears.

Even though I only have one graphics card, unlike the author of the above post, I was still able to uninstall and even delete it. Then I reinstalled it using a driver found on the Radeon website.

And GREAT, I have my 2 screens. I have my 2 screens, but once again I launch Fortnite and the same problem arises consistently.

Also, when my 2 screens display the same thing, no matter what game I launch, it runs at 15 fps at most instead of the usual 60+, I suspect the problem comes from the graphics card more than from the monitor.

I am therefore stuck without a solution. Thank you for your help.