1 year of struggling with random GPU shutdowns/power management issues; help!

As in the title, I have a hack built Sept 2020 (pics and details in link) using OpenCore, updated to approx. Feb '21.

*Hardware\*

CPU: Intel Core i9-10900K 3.7 GHz 10-Core Processor

GPU: Sapphire Radeon RX VEGA 64 8GB NITRO+

Motherboard: Gigabyte Z490 Vision D ATX LGA1200 Motherboard

RAM: Corsair Vengeance 64GB DDR4-3600

Audio - none, Connected through USB: Focusrite Clarett 2Pre USB Audio Interface

WiFi/BT: Fenvi FV-T919 Wifi/Bluetooth Adapter

Power Supply: Silverstone SFX800 80+ Titanium SFX POwer Supply

Other: Ableconn USB-C Expansion Card

*Guide\* - Dortania OpenCore with some help from SchmockLord's Github

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*Issue\* - I will have semi-random DumpGPURestart or other GPU-labeled crashes. Sometimes they happen with no warning, other times it happens when I plug something in. I suspect it has something to do with power management, as the problem seems to increase/replicate when I use USB-C cables meant for fast-charging. (Recently, I used a fast-charging USB-C cable to plug my audio interface into the USB-C expansion card, and these shutoffs started happening multiple times an hour).

When this happens, no amount of hot plugging will get the screen back and I must do a hard reboot.

It happens more when using USB-C ports and also more when using the regular USB ports on the front of the case, rather than the back.

Today, it happened when I plugged in a Launchpad X controller using a USB-C to USB-A cable that usually charges something else. I got the following console message:

AMMuxedDevice Disconnected / DumpGPURestart

Often I notice that there seems to be a lot of these AMMuxedDevice Disconnected.

Here is another screen grab from a different random shutdown, I believe this one was unprompted:

Another AMMuxedDevice

And another

And another.

Please help, I've been stuck for a year!

I've tried:*Taking it apart and putting it back together (checking loose connections)

*Upgrading OpenCore

*Many different graphics/framebuffer settings in the config.plist

*Various USB port mapping profiles, I have made sure i'm within the port limit

*No longer using the USB-C expansion card ever and only using the onboard thunderbolt ports (this does improve things a bit)