Textures/lighting flicker/flash in most games (New Build)

[Rulemeister]

My brother's desktop recently died so we decided to build him a new one.  Specs are:

 

MSI x570 gaming plus

Ryzen 5 3600

2x G. Skill Ripjaw V 3600mhz 8gb

EVGA 850w PSU

EVGA GTX 1080 FTW Hybrid

Samsung m.2 500gb drive (and another m.2, can't recall the brand)

 

Problem is, it runs perfectly on exactly 2 games, Diablo 3 and Path of Exile.  For every other game we've tried (Borderlands 3, Overwatch, Valorant, Spellbreak), and on the Unreal benchmarking tool, we get character models twitching back and forth (like in the Valorant champ select) and textures flashing in and out (pieces of walls and objects).  The lighting in the benchmarking tool twitches too and the shadows twitch with it.  It varies between extremely annoying and unplayable.

 

Here's everything I can think of that I've tried so far (in no particular order):

Fresh DirectX install

Swapping his 1080 for mine (both work in my setup, and have the same issue in his)

Wiping drivers with DDU in safe mode and updating Nvidia drivers (tried current and one from about a year ago)

Updating the BIOS

Changing the GPU PCI slot

Completely formatting drive and fresh windows install with no internet connection, manually updating drivers from usb

Not adding Valorant after fresh install

Running windows off each m.2 individually (removing the other)

Swapping RAM slots, using 1 stick at a time in multiple different slots

Under- and overclocking RAM (seems like I get a slight improvement with slightly higher voltage than default [1.35v to 1.4v] at 3600mhz but definitely not fixed), with/without A-XMP enabled

Under- and overclocking GPU with Precision X1

Swapping everything to an old case and reassembling (GPU felt like it might not be fully seated in the one case)

Checking temps (everything under 50 C max during benchmark) and voltages (I'm definitely no expert on this part but his OpenHardwareMonitor readout looks pretty identical to mine)

Changing monitors (don't remember what models off the top of my head, but one runs at 144hz, verified with the monitors on-screen display. The other was an old 60hz monitor)

 

One thing that bothers me is that his hardware explorer in the MSI BIOS gives details on all his components (name, model) but for his PCIe where we have the GTX 1080, it only list "VGA compatible controller running at x16" (I don't have an MSI board so I'm not sure if this is an indication of a lack of driver or just normal).  Device manager says GTX 1080 and says it's working properly. 

 

Only drivers I've been manually installing are the AMD chipset from MSI's website and the Nvidia drivers.

 

I'm completely stumped.  The fact that there is no hint of the issue in D3 or PoE, but that its pretty bad in everything else makes no sense to me. Nothing I've tried seems to have helped even slightly except for maybe the RAM tweaking (and the improvement doesn't seem consistent).  I've built 5 or 6 setups and never had a problem like this.  If we have a bad part, I don't know which one to suspect. I also feel like I might be missing something obvious. 

 

Any help would be extremely appreciated.  And I apologize in advance if I'm slow with updates/more info, I have to drive to his house to mess with it.

[Rulemeister]

Oh and the BIOS I updated to was 7C37vA84 (beta, released 5/15/20).

 

I don't have footage of the issue, but the flashing textures is similar to these videos I found (but worse than this and on more objects/surfaces):

 

 

 

 

[Rulemeister]

Bumping once more to see if you guys have any suggestions.  There's nothing else I can think of besides taking it somewhere to have the board/cpu tested.  Is there a good diagnostic software for this kind of issue? Anything that could give me a hint on what to focus on would be awesome.