GPU issues

I think I’m dealing with a failing GPU. It started out weird—my screen would just go black and sit there flashing "entering power save mode" constantly. I thought maybe I had just bumped a cable since I was using an old one from a previous build, and swapping it actually fixed the display issue... for a moment. But then the whole system just shut itself down. When I tried to boot back into macOS, it wouldn't cooperate. After letting it sit for a while, it finally kicked back on, but now everything is stuttering. I'm seeing these annoying lags during web browsing, but it's most noticeable in-game—where it's absolutely crawling despite the counter claiming I'm getting over 200 FPS. This has never happened before, and I've only had this rig for about six months. Based on what I've read online, my gut says it's the graphics card... I'm just not sure if there's anything I can tinker with myself, or if I should just bite the bullet and take it to a repair shop.
Specs: Intel Core i5 CPU
NVIDIA GTX 1650
Corsair RM650
ASUS
Crucial 8 GB 1Gx64
HP Monitor

Hey, have you actually tried slapping some fresh drivers on there yet? http://support.amd.com/en-us/download/

I suspect it’s either a dead CMOS battery or a faulty ASUS motherboard if we're talking hardware. Otherwise, it could just be an issue with macOS—maybe some corrupted files or a malware infection is messing things up.