I have two screens. If I play Fortnite and watch YouTube or search for something, my whole PC suddenly freezes - that means I can't press anything anymore and have to switch the PC off with the on / off button. What is that, please?
Maybe your memory is running full…
Which parts are built into your PC?
What are the temperatures and the load on the parts?
What is actually built in?
GTX 1070
AMD Ryzen 5 3600
16GB RAM
Msi B450M
If you don't have enough RAM, the RAM will fill up and freeze.
Solution: upgrade RAM
(If it's the problem)
How are the temperatures and the load before it crashes?
Had the same problem. If your operating system is Windows, enter "Event Viewer" in the search bar at the bottom. After opening it, you go to "administrative events". Warnings, criticisms and errors are displayed there. Look at the reason from there. Then I can help you.
16GB RAM is probably enough.
That's enough