Question New computer suddenly freezing. Crashing to desktop during games.

[Snibbit]

I checked a little over 20 pages of the forums yesterday, trying to find the exact same issue I've been having, but I'm still not certain on what's causing my issue. I'm leaning towards the PSU, perhaps the GPU, but maybe someone here will be able to shed some light. I've also tried posting this in a number of other places, but no responses so far.

Specs
Custom Build: All parts bought around June, except HDD which was bought end of last year.
GPU: AMD Radeon RX 5700 XT Red Dragon 8GB. No overclocking.
CPU: AMD Ryzen 5 3600. No overclocking.
Heat Sink: CRYORIG H7.
Mobo: B450 Tomahawk Max. Firmware version: 3.50.
RAM: Corsair Vengeance LPX 16GB (2 x 8GB) 3200MHz. No overclocking. Put in as motherboard manual directed.
PSU: Corsair TXM Gold 550W.
SSD: Crucial MX500 250GB. (157GB free).
HDD: Seagate BarraCuda 2TB. (1.38TB free).
Case: NZXT H510 (Replacing soon).
Fans: 2x intake: BeQuiet! 120MM Pure Wings 2, 2x exhaust: Noctua NF-P12 Redux. Definitely put the right way around.
Operating System: Windows 10 Home. Version 1903. 64-bit.
GPU Drivers: Adrenalin 2020 Edition 20.4.2.
Chipset Drivers: AMD SMBus. 5.12.0.38.
Programs running during issue: Steam, Discord, Logitech G Hub, SteelSeries Engine 3.

Issue in brief

• Games that had been running smoothly, suddenly freezing and crashing to desktop.
• Sound is fine during these crashes.
• Computer doesn't require rebooting (except one or two exceptions) and no BSOD.

Issue in more detail
Since I made this computer in June, everything had been running fine, with the very occasional mini lock-up when browsing. In the 2 weeks prior to the first problem, I had played roughly 20 hours of Divinity: Original Sin 2 (Through Steam) and it had run flawlessly. One morning, I played for a few hours without issue, took a break, did a little bit of work and went back on. The game froze and crashed to the desktop a few seconds later without an error. During the freezing and the crash, I could still hear everything on Discord clearly. The game did the same thing another 3 or 4 more times in the next 10 minutes. Later, after it had been stable a while, I started to see white, flashing graphical glitches appearing in-game when viewing things from certain angles. A game reboot didn't fix this, neither did a computer reboot. The game crashed again a while after, but this time needed to be force closed with task-manager.

The next day, I tried another game (Forza Horizon 3) and it ran absolutely fine for an hour, until suddenly freezing and crashing to the desktop. There was no stuttering or warning signs before it happened. But, again, Discord was completely clear.

I've had a couple of other issues in this time. One being when typing into an address bar (Firefox), my computer locked up, the screen went black for a second and then everything came back and the typing I had been doing appeared in the address bar. That's only happened that one time. Another time, my computer fully locked up and had to be force rebooted when I tried to load up AMD Ryzen Master.

Troubleshooting attempted

• Ran several tests using BurnInTest, all coming back with no errors.
• Stress tested my RAM for 40 minutes using OCCT, again with no errors.
• Ensured all drivers are up to date.
• Updated Windows.
• Scanned using sfc to repair corrupted files.
• Done a full virus scan with Windows Security.
• Monitored temperatures with HWMonitor while gaming (Around 40 - 50c for CPU, 60 - 70c for GPU).

Sorry for the long post, but I wanted to include as much information as possible.

If anyone has any ideas, I'd be extremely happy to get this sorted.

Thanks!

 

[Snibbit]

-UPDATE-

I have undervolted my GPU slightly and the graphical errors have gone and there's not been a crash in an hour and a half of gameplay. Could this mean that my PSU wasn't providing enough power and could potentially be faulty? Also, I've noticed that, according to OCCT, my RAM is set to 1066 frequency; that should be higher, I believe?