Question Computer hard crash after using my graphics card

Jun 12, 2021
Hello, i have a pretty old system using APU, and my younger brother bought a graphics card for a 'Minor" gaming upgrade (considering the APU).
After some time, the computer started crashing in games, and after some other time it also started crashing when idle on desktop. Crashing meaning like the PC cant interact at all and needs a hard restart/shutdown (no BSOD). I found a small work around for idle to minor workload with the Wattman -10% power adjustment. But then in games it might crash up on me like that. The configuration without the Graphic card works without crashes, and also gave the graphics card to a friend to test it for 3 days and no crashes on his system also. Tried several video drivers but no hope. Updated to latest bios drivers. Can someone enlighten me?

Mobo: ga-f2a68hm-s1
Cpu: A10-7890K
Ram: 2x4GB Mushkin 2400Mhz (mostly using it 2133 Mhz stable with my apu)
PSU: Corsair CX 600
GPU: RX 570 8GB Armor edition (using a display port to vga adapter for the monitor as it has only vga)