Is my motherboard dying? "The system experienced a boot failure"

[Kywim]

Hello!

 

Currently, my computer is giving me some trouble.

• On Friday, my computer crashed while I was away. I've came back to it rebooting. Nothing in the event log to help me except the critical error "The last shutdown was unexpected". My computer was fine for the rest of the day.
• On Saturday, when I started it, it shut down nearly immediatly (5 seconds after pressing the button), restarted and prompted me with a message. https://imgur.com/gallery/HegDaeB "The system has experienced a boot failure". I went into the BIOS, changed my VCore back to where it should be (1.2V instead of the default 1.44 for a 4790k) and booted into windows fine. I even ran some benchmarks which you can find below.
• Today, when I started it, it seemed fine, except I had no video output. Nothing, just a black screen. I wasn't even booting into windows! (No sound and pressing the power button once to shut the computer down didn't do anything). So I pressed the reset button, restarted it, and it did the same thing as Saturday: Boot, shutdown, Reboot, "Boot failure detected". Same thing as yesterday, I went into the BIOS, changed my settings back to where I want them and booted into windows fine.

Benchmarks I ran:

• Superposition : Score is fine (5.78k on 1080p extreme)

• Cinebench CPU: Score is fine (580)

• FurMark + Prime95 for 10 minutes : Fine. HWInfo64 Logs available here

My setup:

• CPU: i7 4790k
• MOBO: Gigabyte Z97x UD3H
• RAM: Corsair Vengeance 1600mhz RAM
• GPU: EVGA GTX 1080Ti FTW3 (Brand new)
• PSU: EVGA G1+ 1000W PSU (Brand new, came back from a RMA'd G1+ 850w, so it was tested by EVGA before being sent to me)
• Boot drive: Samsung 850 Evo 500gb SSD
• Secondary drive: Seagate barracuda 2TO

 

I don't know what to do. Windows doesn't help me locate the issue (no logs/dump/bsod), my computer is fine when I manage to get it into windows (played all day yesterday without any trouble). The only thing that I can think of is the motherboard that's dying. My HDD is also a bit old and makes weird noises but I don't think a bad HDD can cause this? It's fine and I can access every file in windows.

 

How can I find out for sure what's wrong?

Thank you.

[Master Disaster]

You've been running your 4790K @ 1.44v? What cooling do you have?

[Kywim]

Just now, Master Disaster said:

You've been running your 4790K @ 1.44v? What cooling do you have?

I am not. It has always been running at 1.2v, but the motherboard's default setting is 1.44v because Gigabyte thought it was a good idea, so the first thing I always do when my BIOS settings are reset to default is changing the vcore back to 1.2v.

[Master Disaster]

1 minute ago, Kywim said:

I am not. It has always been running at 1.2v, but the motherboard's default setting is 1.44v because Gigabyte thought it was a good idea, so the first thing I always do when my BIOS settings are reset to default is changing the vcore back to 1.2v.

Ahh, phew. Yeah my MSI does a similar think to my 6700K though not to that extreme.

[Kywim]

Bump. I really need help on this. I don't even know where to start troubleshooting if the system is fine when it boots!

[Kywim]

Hello, I'm in immediate need for help. My computer now refuses to boot. I decided to keep the "optimized defaults" when I managed to get it to boot earlier, but now it simply refuses to boot. All I have is a black screen, no signal. All the fans spins, my GPU's RGB lights up, but there is nothing both from the onboard GPU and my 1080ti's hdmi output. The reset button doesn't work, the only thing that works is a long press on the power button to shut the thing down

 

How can I diagnose what's wrong? I had trouble booting for the last 2 days but when I managed to boot my computer was always fine and ran flawlessly.

 

I suspect that the motherboard is dead (I've ruled the psu & gpu out since they are brand new). How can I confirm it?