New build screen flicker/static

[Prune_Picker]

Hello. I just put this pc together for my wife (part list below). Everything went smoothly until i installed the display drivers for the vega igpu. Now the screen flickers, shows rainbow static for a second, and sometimes the pc freezes whenever it is put under a load. I can trigger it pretty reliably by either running cinebench or any graphically intensive game. When idle or doing only basic tasks, it flichers very infrequently if at all. When starting up, about 75% of the time, it will show a blank screen where the windows lock screen should be. Restart a few times and it will boot to windows. I can uninstall the drivers or start in safe mode and it stops, but obviously with only limited functionality. I am a relative newcomer to pc building, but based on search results, i have already tried the following:

-Different monitor and hdmi cable - no effect 

-Adjust ram speed and voltage (ended up enabling the xmp profile - seemed to help a little) 

-Higher wattage psu connected temporarily - no effect

-Older drivers, since someone said the same thing started after updating drivers on their existing build - no effect

-Maybe a few other things i can't remember.

 

Parts: (copied from pcpartpicker)

 

CPU: AMD Ryzen 5 3400G 3.7 GHz Quad-Core Processor

Motherboard: ASRock Fatal1ty B450 Gaming-ITX/ac Mini ITX AM4 Motherboard

Memory: G.Skill Aegis 32 GB (2 x 16 GB) DDR4-3000 memory

Storage: Samsung 970 Evo 1 TB M.2-2280 NVME Solid State Drive

Case: Cooler Master MasterCase H100 Mini ITX Desktop Case

Power Supply: be quiet! SFX L POWER 500 W 80+ Gold Certified Fully Modular SFX Power Supply

 

Thanks in advance for any insights.

[Playlogo]

Is your Mainboard "RYZEN 3000" Ready? And have you updated the bios?

[Prune_Picker]

Yes, the board was ryzen 3000 ready out of the box, and i also updated the bios to the latest version to try to troubleshoot

[Prune_Picker]

Update: i played around with ram speeds some more, settling on 2933 mhz and 1.35v. That helped alot, but the pc still fails to output video when booting to windows more often than not, and it still flickers occasionally under load. Huge improvement though. The pc is usable for the most part, and in the mean time, i have contacted amd about the issue