PC restarting automatically. Need to check if GPU or PSU is at fault.

Config:

CPU - AMD 3700x RAM - 4x8GB Corsair GPU - Powercolor 5700XT Red Dragon PSU - Corsair RM650

OS is running off of an Intel SSD.

This started happening a couple of weeks back. The issue is intermittent. Whenever I'm playing a game, the PC automatically restarts. Sometimes it happens within 5-10 minutes. Sometimes I can play for hours without any problem.

I've already ran memtest and prime95 and didn't face any problems with either RAM or CPU.

I've mostly faced this problem while playing Sniper Elite 4, but on couple of occasions it happened while playing Destropolis - a rather lightweight twin stick shooter.

Earlier this month I was playing Spider-Man without any problems.

Now I'm wondering if the GPU is going bad or if the PSU is going bad and is not able to provide enough power.

Is there any way to conclusively understand which component is malfunctioning before I can start the RMA process?