Odd issue; Black Screen, no HDD activity

So starting yesterday, I began to experience this odd issue, it started after a session of GTAV with a friend, my monitor went black and no sound was coming from my headphones, and looking to my case, there was no HDD activity as well.

The second time it happened was an hour later after I left my PC to idle for around 15 or so minutes, came back to find no picture after moving the mouse around and no HDD activity.

And the third instance just now, when I returned from making myself a meal, found the monitor in the 'off' state like it had done the previous two times after loosing picture and no HDD activity.

CrystalDiskInfo shows nothing, Event logs only shows the unexpected power loss from me doing a hard reset, no signs of anything overheating, Malwarebytes finds nothing, and nothing has changed for roughly a week before the problems began to occur. I'm pretty worried given I've barely scrapped money together to make this thing the way it is.

Anyone have any idea where to look next to solve this issue?

Update 1: Had it happen again whilst watching Youtube. Video cuts out, no more sound, no HDD activity, rebooting has no issues and no BSoD message that usually pop's up after a BSoD.
Ran a ChkDsk on my C drive, waiting to see if the issue recurs, still looking for suggestions as Google isn't coming up with anything.

Update 2: Problem happened once more with same symptoms whilst simply having FireFox open. PC with issues currently off and now reporting from laptop.

Update 3: Reseted RAM modules and switched occupied slots while I was at it. Also cleaned and reseted GPU and inspected card, no abnormalities found.
Inspected motherboard as well. No abnormalities found.
Proceeded to dust out unit with compressed air.
Unit currently booted into Safe Mode.

Update 4: Unit has held in safe mode for an hour without issue, considering issue may be driver-related which oddly enough shouldn't be the case since they haven't recently been changed, but not ruling out other possibilities either.

After reseating the GPU in it's PCI-E slot, reseating the RAM, and changing the power input it the GPU was using on the PSU, the issue had vanished, and just now it had returned. same symptoms as before.
GPU was roughly 60C at the time with a game on and there are no artifacts on screen at this time, although there looked to be some at the top of the screen after an unsuccessful attempt to boot into safe mode with networking, but the artifacts are no longer present, I think it's just like that as I remember seeing the same artifacts with a GTS450 years ago.
Anyone have absolutely any idea what's happening? Anything that can help?

It's happening once again after running fine for a week after replacing the DVI cable with an HDMI last time it happened.
It also happened in Safe-Mode with Networking when I was going to attempt updating my Nvidia drivers.
I just want to fix this and not have to worry about it happening all the time.
Help.

Your problem could be a tough one to find. To me it smells like a power supply, which is very hard to diag.

I would start by making sure Sleep and Hibernation are disabled.
Then make sure the monitor is set to Never turn off.

Could you look in Event Viewer to see if their is anything related to the time stamp of your problem?

Go into bios and see what the
3.3 volts =
5 volts =
12 volts =

Monitor is set to turn off after 10 minutes, but this issue happens whilst the system is in use. Both sleep and hibernation are disabled.
In even viewer, I only get event IDs 41 and 6008 which is from the hard reset, which shows the hard drives may still be active, even if the HDD light isn't lighting up.

And if you're asking about motherboard voltages, Speccy displays the information as well instead of having to get into BIOS.
3.3V - 3.231 V
5V - 4.948 V
12V - 12.188 V

And just checked to be sure, and I can't find voltages anywhere in BIOS.

Well I can't find any voltages like I requested in Speccy.
Post me a picture if you can. Maybe I'm missing something.
I just updated to the newest version and still can see all those voltages.

Use this tutorial by Brink to post snap shots.
Screenshots and Files - Upload and Post in Seven Forums

I haven't used a Intel motherboard in many years so I don't remember anything about the bios.
According to your posted volts look okay. It would be handy if we could get those same volt readings with the system under load.

Could you look in Reliability Monitor and see what you can find?

I presume you have checked all connection to the motherboar, video card ect.

Attached image shows voltages which are under the Motherboard section of Speccy.
I looked through every section of my BIOS and no voltages are available in what you had listed.
Speccy also doesn't appear to update voltage readings in real-time, if there's a way to do so, so i may test it under load, I'd be happy to know how.
As for reliability monitor, it only lists the unexpected shutdowns that have resulted from the black screens, as hard-resetting is the only way to recover.
And yes, all power connections have been checked to be secure multiple times.

As Layback Bear opined, this could be a very difficult nut to crack.

I had one new AMD processor which will keep the PC running as long as you don't do anything with the PC :). Start running a program and depending upon the crunching it requires, the PC will shut off at varying times.

I also had another PC doing this. In this case it was the graphics chip on an MSI motherboard. MSI service changed it.

I would suggest you to carryout a stress test and check whether that can locate the component causing the problem.

https://www.raymond.cc/blog/test-sys...tem-resources/

Only a professional Service point can substitute various "removable components"( including the Power Supply) on a PC in an effort to find the offender. If such removable components are not the cause then one of the fixed components on the motherboard.

The strange thing is, that this issue can occur from everything from playing a game so simply being idle, which is confusing. And the system had run smoothly for the while I had this setup before issues began to occur.

I'll check out those stress-testing programs and see what happens, but I currently theorize that my GPU may be faulty, or the power supply to the GPU, which is a modular connection, may be faulty in some way. If it happens again, I'll be throwing in my old GTS 450 to see how it runs.

Update:
So a few things, put PC through a medium/heavy load cycle and used HWMonitor to look at voltages and temps.
All temps stayed in their normal levels, the processor being a 1st Generation i7 being naturally warm in the high 50's/low 60's.
Voltages are as follows:
+1.5V:
Min: 1.107V
Max: 1.107V

CPU VCORE:
Min: 0.926V
Max: 1.230V

ATX +3.3V:
Min: 3.231V
Max: 3.231V

ATX +5V:
Min: 4.992V
Max: 4.948V

ATX +12V:
Min: 12.125V
Max: 12.188V

There is one thing I've noticed through these weeks of having this issue though is the temporary fix; If I flip the switch on my PSU, unplug everything, reseat the GPU in the PCI-E x16 slot, reseat the 8-pin power connector for the card, then set it all back up, the issue will temporary disappear for about a week before happening again. Hopefully that alone may provide insight as to what may be happening, as I'm still clueless.

Update 2:
Ran a good two hours of GTAV as a test to see what changes would appear on HWMonitor under a game that puts a heavy load on components such as GTAV.
All voltages are exactly the same across the board except for the ATX +12V which only had a different minimum value of 12.063 V.

Bumping topic.