Monitor switches off but computer still runs

Roterblade

TS Rookie
So basically, my computer has stated to do this annoying habit where the monitor will switch of however the the computer itself continues to run, in addition when this occurs my fans start to make a lot of noise which I assume is speeding up; why? I don't know. This generally occurs after 30 mins to hours for this annoying event to happen.
This mostly happens during playing games which some may name as taxing games. This "monitor turning off thing" event seems to happen so far on: Rainbow 6 Siege, Destiny 2 and Fortnite.
For additional info here are some specs for my PC and graphical settings for my games:
Computer: • Asus strix 1660ti
• Asus strix B450-F
• Ryzen 5 2600 (stock cooler)
• Corsair 4x4gb LPX 2666mhz RAM
• Corsair RM 650x (80 gold +)
• 1TB HDD & 500gb SSD
• 27" 60hz 1080p acer monitor (https://www.amazon.co.uk/Acer-S271HL-inch-Widescreen-Monitor/dp/B01ANB3KDY ) Connected via HDMI
P.S All these components were bought only a month ago. The graphics card however was bought only a few weeks ago.
Thank you for reading this <3