BRAND NEW PC SHUTTING DOWN AUTOMATICALLY

New PC randomly shuts down completely under load — need help diagnosing

Hi everyone, I recently built a new PC and I'm having a serious stability issue. The PC is only around one week old, and it has completely powered off three times.

PC Specifications

- CPU: Intel Core i5-14400F

- GPU: Gigabyte Radeon RX 7600 8GB

- Motherboard: Gigabyte B760M DS3H WIFI6E GEN5 DDR4

- RAM: Corsair Vengeance LPX 32GB (2×16GB) DDR4-3200

- SSD: Crucial P310 1TB NVMe

- PSU: Corsair 750W Bronze

- CPU Cooler: Intel stock cooler

- Case: Gigabyte C200 Glass

- Monitor: LG UltraGear

What happened

I've had 3 complete shutdowns so far:

1st shutdown — OCCT Power Test

I used OCCT's Power test to stress the system and check stability/power delivery.

The PC ran for approximately 9 minutes, then suddenly powered off completely.

Temperatures during the test were approximately:

- CPU: 88°C average, 94°C maximum

- GPU: 72°C average, 75°C maximum

2nd shutdown — Black Myth: Wukong

I then played Black Myth: Wukong.

The PC shut down during the opening cutscene/fight.

temperatures were below 50°C for both the CPU and GPU at the time

Again, it was a complete power-off — not a game crash or Windows crash.

3rd shutdown — OCCT Power Test

I ran the OCCT Power test again to see if I could reproduce the issue.

This time, the PC lasted approximately 13 minutes before completely shutting down.

The temperatures were again around:

- CPU: ~88°C average

- GPU: ~72°C average

What the shutdown looks like

There is no BSOD, no Windows shutdown animation, and no warning.

It is simply:

PC running normally → sudden black screen → PC completely powers off.

The PC doesn't automatically restart.

What I'm trying to figure out

The PC is brand new, so I'm particularly concerned about a faulty component.

Any Clue ?