[SOLVED] Computer crashing on gaming can't find cause.

[ViridianZe]

My computer keeps crashing(black screen reboot) and i can't find the cause I tried running some tests myself first singularly then I blasted everything to try and cause it to crash nothing happened so I took it into a PC place and they couldn't get it to crash either but if I play a game some will crash my pc at the moment from what I can tell Valorant, rocket league, Dragon age, and oxygen not included has this effect other games do as well but it is less consistent a list of things I've tried to find cause are

.Reinstall GPU drivers completely
.change power cables and sockets
.temperature checks
.Messing with power settings in control panel
.cleaned dust
.Took to a diagnostics specialist(got a weird reason but not sure if it is accurate will explain)
.Downgraded resolution from 4k-2k-1080p same effect
.Checked fans they are fine
.Ram is fine passed all tests
.Pushing GPU in tests on 4k does nothing
.Tested hard drive no error that i can see using Samsung magician (SSD)
. I even manually touched my parts while running to see if temps were lying
---
They only changing factor is my Monitor which I upgraded from a Dell something office 1920x1080 to an Acer 4k monitor and i told the specialist was that my monitor had changed he came back and said my CPU may not be compatible which I've never heard of anyway ill list my specs now haha.

Specs
-------
.Gigabyte GeForce RTX 2070 8 GB WINDFORCE Video Card
.intel Core I7-8700k 3.7GHz 6-Core Processor
.be quiet! Dark Rock Pro 4 50.5 CFM CPU Cooler
.Acer Gaming Monitor 28” KG281K bmiipx 3840 x 2160
.Asus Prime Z370-A ATX LGA1151 Motherboard
.Corsair Vengeance LPX 16 GB (2 x 8 GB) DDR4-3000 CL15 Memory
.Samsung 860 Evo 1 TB 2.5" Solid State Drive
.EVGA SuperNOVA G3 650 W 80+ Gold Certified Fully Modular ATX Power Supply
.Microsoft Windows 10 Home OEM 64-bit
-------
when it crashes i get an audio cut the fans stop but there is a light on the motherboard that pops up white which I'm sure is just rebooted light everything just turns off and starts up like i unplugged and replugged.

Any help would be appreciate this is killing me so much

 

[mdd1963]

Disable MCE in your BIOS during testing if it is enabled, as not all CPUs are for sure 100% stable at max turbo across all cores at whatever voltage is currently provided.

Run your RAM at default 2133 MHz or 2400 MHz speeds during testing....

Last but not least, certainly a marginal/failing PSU can 'brown out' under gaming loads, causing assorted faults /reboot/lockups... (if you change PSUs, be absolutely certain to not mix modular cables between the two units, as many use different pinouts at PSU's connection points, which can fry things quickly, as many have expensively discovered in dismay.