Random PC full shut off, not overheating, but maybe due to high GPU load.

Playing 'certain' games my PC will switch off. I'll get a black screen with no error message nor "shutting down" text like when you switch off the PC manually. I am able to instantly power the PC back on. In my error logs I have a the following note when checking after the power off, "The previous system shutdown at 22:19:12 on ‎13/‎09/‎2025 was unexpected." with the code 6008.

SPECS:

• AMD Ryzen 7 5700X3D 8 core
• Sapphire Radeon RX 7800XT 16GB
• Asus Rog Strix B450 F Gaming Motherboard
• 32GB (8GBx4) Corsair vengeance DDR4 3200MHz
• CORSAIR RMe Series RM850e Fully Modular 80PLUS Gold ATX Power Supply
• I boot from an SSD (Sandisk Ultra II), have a WD Black 1TB NVMe, another Gigabyte SSD 500GB and a random HDD 1TB for basic storage.
• I play at 1440p 120hz, usually anywhere from 60fps to 120fps depending on the title.

I've ran benchmarks, using both furmark and prime95, both individually and together with no issues, I couldn't replicate the problem.

The 3 games I've had this happen in are:

• Tokyo Xtreme racer 2025 (when it released, haven't played since the first month)
• Wuthering Waves, happened about 4 times in the same location, but not in others. I did later cap at 60fps to reduce load and this probably has helped reduce the issue.
• Borderlands 4, has happened twice.

The interesting thing is as mentioned in the title, this seems to happen when the GPU is under high load. With my settings for Borderlands 4 its usage goes between 80% and 99% ish depending on what is happening. With Wuthering Waves, I believe it was similar, I was trying to run 120fps and it'd be under high load. With Tokyo Xtreme Racer I can't remember. However, sometimes I can be playing said game for about 3 hours or so and it's fine, sometimes shorter and it can happen. It never happens in general use or on low load.

I actively watch my temps since this started happening and my CPU never exceeds around 55C to 57C when playing demanding titles. My GPU at high load will sit in the 70C range.

I often read it's the PSU according to the tests I've made, I don't have a spare unfortunately. I've re seated all the cables before and RAM too.

Is my PSU giving enough power, or does it sound faulty? If I was to change my PSU, should I get a similar powered one or go for more?

Thank you for your time and help with this.