Question Previously fine computer no longer booting

Apr 7, 2020
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Hi all

I'm a complete newbie to the forum - so hello, and thanks so much in advance for anything you can help me with!

First, specs:
  • Intel i7-7700k
  • ASUS STRIX GAMING Z270F Mobo
  • 16GB (2x8GB) Corsair Venegance LPX DDR4 3200 (XMP Profile enabled via ASUS BIOS)
  • STRIX GTX 1080 Ti
  • Thermaltake 750w
  • 3 SSDs (one NVMe) plus one HDD; no CD/DVD
  • All fan cooled (CPU is after-market Arctic Freezer; case has 3 140mm intakes, and 4 120mm outtakes)
So, here's the story:
  • I've had this setup for a while - the last hardware change was installing the NVMe about 6 months ago. At no point since have I put my hands in the case.
  • It's worked fine without any issues/quirks up until Sunday morning. On Sunday, I booted as usual to a POST recovery message - the usual "Press F1 to recover BIOS settings".
  • I run through, updated the clock, put XMP back on, adjusted fan profiles and I was on my merry way. Used the system for the full day (including a restart and shut down) with no issues.
  • On Sunday night I shut down and switched everything off at the mains. Yesterday, I had to go through the same POST/settings/reboot sequence ahead of a full day as usual.
  • Last night I switched off at the mains again; this morning it's extra weird: pressing the power button switches the system on for about a second, it then completely powers off, then a couple of seconds later powers back up and starts normal boot process.
  • Unfortunately though it stops there - I get nothing on the display (not even the BIOS message), and the DRAM LED is lit solid orange.
  • That's where I'm at now.
Here's what I've tried so far:
  • Disconnecting and reconnecting all cables.
  • Battery replacement and CMOS jumper reset.
  • 1 RAM stick at a time (alternated), and in each of the four slots (the DRAM LED prompted this).
  • Removing and re-seating GPU.
  • Replacing GPU and PSU with spares (GTX 1070 / Corsair 650w) - both working in another PC.
  • Updating the BIOS (one one of the occasions I did manage to get in - using the Internet option through the BIOS itself. It loaded up fine after this).
So I'm at a loss as to what I can try next so would really appreciate some suggestions! I'm happy to accept that I need to replace something, but I'd rather have a solid idea where the problem lies to hopefully prevent me having to replace most of the rig. The obvious culprit to me was the RAM, but I've had no previous issues with my RAM, and have tried alternating the two sticks. I guess it's possible they could be faulty - but for both to fail at the same time seems rare?

I thought the GPU might to be to blame - but a replacement has the same issue. This boils down to me to either the mobo or the CPU - unfortunately I don't have similar socket replacements to try these out.

Any advice you can give me - no matter how obvious - would be really appreciated. Please ask away if you have any questions!

Thanks
J
 
What I particularly unusual, is that you say you had to go through the "usual BIOS setup" rutine everyday. Unless I misunderstood you, that is anything else than usual.

So just to clarify, since I most likely misunderstood you - for how long, have you had to setup BIOS before using it for a day? Only since sunday, or for longer than that?

Also, when you say you disconnected it at the mains, do you mean you turn off power at the wall power outlet in addition to powering the PC down?
 
Apr 7, 2020
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Thanks for replying.

Sorry, probably me not making myself clear! I've only had to go via the F1 button (to reset the BIOS settings) for the last few days. Before that, it was a normal boot-up sequence (power button > POST flashes up > Windows loads). I meant "usual" in the context of the days surrounding.

Each night I shut down my PC and then switch it off at the mains. I obviously wait for the full shut down to complete before flicking off the wall socket.

Thanks again
J
 
Actually, you explained it perfectly fine. But english isn't my first language, and once in a while, some words are not very precise when translated to my language. So I thought it was best to ask about it

Unfortunately I don't really see anything obviuous right now. Some of the symptoms you describe, like BIOS not saving settings, you have already tried the obvious fix for - which is replacing the CMOS battery with a new one. You also changed PSU

BIOS generally reset settings due to lack of power to the BIOS chip.

Although not strange, disconnecting all power from the system after completed shutdown, is the only other immediate thing that stands out to me because of the resetting of BIOS settings after a period of time without power, but I'm not neccessarily seeing a connection to your problems straight away.

--Have you tried shutting the PC down as you normally would, but leave the mains on overnight, just to see what happens with regards to the constant BIOS resetting?

The issues could be related to power - but I'm mostly speculating, and I can't really provide any helpful advice, since you have already performed some troubleshooting in that direction

I hope someone else will drop by shortly, who knows the perfect solution.
 
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Apr 7, 2020
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Thanks, Mads - appreciate you coming back to me.

I went ahead and bought a new mobo, CPU and RAM as I've resigned myself to the fact one of the three is faulty! I'll try the new RAM in the old rig first and it that works I can RMA the new mobo/CPU.