PC keeps crashing and Monitors turning off

This has happened to me 3 times already. While im streaming games, about 2 hours into playing all my applications end up crashing and my monitors turn off for a second then come back on. I'm also noticing my pc is a little bit slower, it sometimes takes longer to load stuff while im editing videos and when moving files and often times the application that i'm on gets stuck and says "not responding" I would like to point out that this recently started happening after I did a fresh reinstall of Windows after I found a virus on my pc.