Monitor randomly gets "No Signal"

Hello, when I am playing a game (eg Gothic 2 on Ultra Graphics or Battlefield 3), the game works for a different amount of time every time, sometimes 5 minutes sometimes 3 hours, then it just freezes for a second and then says "No Signal" on my monitor. When I get this message I have to turn my PC on and off to fix this but when I start playing again the same happens.

I got this PC under a week ago and these are the full specs:
-AMD FX-6300 3.5GHz 6-Core Processor
-Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler
-Asus 970 PRO GAMING/AURA ATX AM3+ Motherboard
-Kingston HyperX Fury Black 16GB (2 x 8GB) DDR3-1866 Memory
-Kingston SSDNow V300 Series 120GB 2.5" Solid State Drive
-Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive
-MSI Radeon R9 380 4GB Video Card
-Corsair CX 500W 80+ Bronze Certified Semi-Modular ATX Power Supply
-Corsair SPEC-02 ATX Mid Tower Case

OS - Windows 10 Pro

I have also placed a extra fan from my old PC in as well as some LED lights.

Cycloid Torus

Posts: 4,870   +1,687
"I got this PC under a week ago"
Builder? Warranty?

Any error codes / beeps? Disconnect/reconnect cable between monitor and video card?