Question Black Screen/No Video Output (checked forums and did due diligence)

[TxRx34]

Error Event: PC was on, with an online game loaded, working just fine. Not actively playing the game, just in idle within the game. PC randomly shut down, producing “Primary Issue”. No known power surge, as all other electronic devices within the area were unaffected.
Primary Issue: PC will turn on, engaging the fans and lights, but it does not have a video output. Does not even get to BIOS menu screen, just behaving as “no signal received”. Motherboard does not have a speaker/beep.
After all the attempted fixes shown below, the “Primary Issue” is still in effect. Tested after each one was completed

• Tested HDMI cable with another laptop to desired monitor. Output worked fine, eliminating the possibility of bad cable and monitor
• Dusted entire inside of the enclosure
• Removed and re-seated the CPU. No bent pins and no burn marks
• Removed old thermal paste from CPU and re-applied new thermal paste
• Reset CMOS via reset button on the motherboard
• Unplugged unit from AC and removed CMOS battery for over 30 minutes
• Replaced CMOS battery with a brand new one (CR2032)
• Unplugged and re-seated all power connections
• Removed and re-seated all hardware devices (GPU, CPU, RAM, etc.)
• Installed an old, known to be working, GPU (Radeon HD 6770) in the same PCIe slot as current 3080
• Installed old GPU (Radeon HD 6770) in secondary PCIe slot, using an old (known to be working PSU)
  • Did not try old PSU with current 3080 GPU (would be under powered)
• Tried to use integrated video output from motherboard (HDMI)
• Used meter to test voltages on ATX pins and CPU pins. All are within spec, per motherboard user manual
• I have a modular power supply, so I tried putting CPU and VGA power into different module
  • Moved "CPU1" to "CPU2" and moved "VGA1" to VGA2"

Motherboard POST LEDs

• Motherboard does have integrated POST LEDs. Per the manual, if a respective LED is lit, that means there is some error with the respective item
• The 4 individual LEDs are for CPU, DRAM, Boot and VGA.
• The LED lights for CPU and DRAM are activated

Specifications

• Motherboard: NZXT N7-Z590 (purchased January 2022)
• GPU: Geforce RTX 3080 (purchased August 2022)
• PSU: EVGA 850W Modular (purchased August 2022)
• RAM: 16GB (2x8GB) Corsair DDR4 3200 (purchased January 2022)
• CPU: Intel i7-11700K (purchased January 2022)

Is there a way I can rule out bad PSU? Bad Motherboard? Everything is basically new. I realize the POST LEDs, but from what I read, a bad PSU can cause those post errors. I'm at a loss with how to determine what is bad, when it can be so many things.

I do not have the option to swap other components or test with other machines.

 

[TxRx34]

{Updated since original post}

 

[TxRx34]

Posted another attempted fix

 

[TxRx34]

posted another attempted fix. Spoke with motherboard MFG and they are sending a new one. Will post if that solves the problem

 

[TxRx34]

Update!

• Replaced motherboard - Same issue. No Post/Display
  1. After replacing the motherboard, the CPU POST LED went away. The DRAM POST LED remains
• Replaced RAM - Same issue. No Post/Display
• Replaced PSU - Same issue. No Post/Display

To this point, aside from the CPU and SSD...everything else is now brand new after doing warranty exchanges on the the mentioned items. Im lost and do not know what to do anymore.