[SOLVED] Help with PC not booting up (not always, tho)

[bonny1992]

Hello everyone!
I don't know if this is the correct category to post into, feel free to move the thread!

Let's start with the beginning.
In mid-2015 I built this PC for my parents for their use (mainly web browsing and some Word/Excel/Outlook), here's the components:

• 
  ■ CPU: Intel I5 4690K
  ■ RAM: Corsair Vengeance Pro (2x8GB)
  ■ MOBO: Gigabyte Z97X-Gaming 5
  ■ PSU: Corsair RM850i
  ■ HDD: WD Red 1TB

After a couple of RMAs (quite unlucky with some components already broken when opened), I managed to successifully build the pc, and it worked until this morning.

This morning I got a call from my father that said that his pc wasn't booting up (my father isn't tech-savvy at all) so I went to the company place to check and, after all, it wasn't working at all.
The pc was stuck in a bootloop divided from simply "not booting up and not even reaching POST" (I believe) and "boots to Windows (extremely slowly) but as soon as I can move the mouse I get a BSOD" (like every time the BSOD was different, too).

What could it be? My suspect are falling to the motherboard but I'd like to be 100% (or the closest possible) sure before buying a replacement.

Here's a small list of what I did (I may have done something else, but I can't remember):

• 
  ■ I tried the automatic startup fix that Windows 10 has when uncorrect shutdowns are happening in a while: after 10 minutes it started rebooting as before
  ■ Detached the UPS from the PC: no changes
  ■ Tried removing the RAM sticks (one at a time, and two together): not even reached POST I believe
  ■ Tested the PSU with the paperclip test: the PSU seemingly was working fine
  ■ Forced the shutdown of the PC holding the button, detached from the wall outlet, then kept pressing the power button for 10/15 seconds, then booting up: it may have worked, but BSOD after the initial Windows loading screen
  ■ Removed newly installed dvd burner (it never worked, maybe I connected wrongly the sata cable): it booted, but once I opened Outlook, BSOD
  ■ Resetted CMOS removing the battery from its socket: bootloop before the POST
  ■ Tried booting in safe mode: after 20 minutes, BSOD
  EDIT: after 20 minutes stuck in Windows loading screen
  ■ Tried booting only with keyboard, mouse and VGA cable plugged in: bootloop before the POST

Also, the BSOD were changing, I managed to take note of the most occured ones:

• 
  ■ MEMORY MANAGEMENT
  ■ IRQL_NOT_LESS_OR_EQUAL
  ■ DRIVER OVERRAN STACK BUFFER
  ■ KERNEL SECURITY CHECK FAILURE
  ■ KMODE EXCEPTION NOT HANDLED

Have you got any suggestions?

Thank you in advance, and sorry about my half-broken english!


EDIT:
Here's a small video of what is happening:
Video on YouTube
When the lights of the motherboard are going off, it's when the PC reboots itself

 

[Supahos]

To bsod in safe mode it's usually hardware

First test would be memtest86 to see if ram dies. Let it make at least one full.pass

 

[bonny1992]

To bsod in safe mode it's usually hardware

That's the same thing I thought

First test would be memtest86 to see if ram dies. Let it make at least one full.pass

I'd do it, but if the pc doesn't even pass the POST most of the time, how can I do this? Placing the ram sticks on a different pc?





EDIT: Updated first post with small information

 

[Supahos]

Memtest runs outside of Windows. If it crashes (after posting) it's definitely a hardware error. Then yes something like testing in another rig may be required.

If not posting you've pretty well limited possible culptits to the ram/power supply/motherboard/cpu

And those are the order id suspect them by likelihood

 

[bonny1992]

Memtest runs outside of Windows. If it crashes (after posting) it's definitely a hardware error. Then yes something like testing in another rig may be required.

If not posting you've pretty well limited possible culptits to the ram/power supply/motherboard/cpu

And those are the order id suspect them by likelihood

Yeah I know that memtest runs separately from the main OS, what I'm saying is that most of the time I all the PC is doing is rebooting constantly, will post a video of it as soon as my brother sends me the one he made this morning.

Also, as I said, I tried booting without any stick plugged into the mobo, but still bootloops, when I expected some kind of error written on screen. (Don't worry, I have written a wall of text, I don't expect someone to read it all )

Shouldn't the PC write some errors if it was the CPU?

 

[Supahos]

It can't boot without ram but the loop is interesting usually when I've done that it'll just stop when it throws a code... Might be moving motherboard up the list and ram down it

 

[bonny1992]

It can't boot without ram but the loop is interesting usually when I've done that it'll just stop when it throws a code... Might be moving motherboard up the list and ram down it

I'm uploading the video on Youtube so I can post it here, sadly neither me or my brother managed to take a full take on one of the rare case when the POST happen to be passed and it tries to boot into Windows.

I'll update the first post as soon as the upload finishes!

In the meanwhile, thank you for your help!


EDIT: I forgot to update this post as well!