[SOLVED] Pc shutoff - now it wont post

[jhuff247]

So last night I'm just chilling, doing literally nothing intensive, just watching a youtube video. Suddenly my pc shutoff, as if we had a power outage, except the fact that everything else in my office was still on. When I went to turn the pc back on, it started fine, no odd noises or anything. However, now it wont post and I never see a BIOS screen.

I built this pc roughly a week and a half - 2 weeks ago. The components include:

X570 aorus elite motherboard
3900x ryzen 9 (no overclock) (stock cooler)
32gb (2x16gb) g.skill trident z running at 3600
660p Intel m.2 2tb drive (boot drive)
1tb wd black high performance m.2
Sound blaster creative z sound card
Msi 2080ti ventus oc 11gb (no overclock)
Corsair RM750 modular 80plus gold psu

The user benchmark had 140%+ across gaming, desktop, workstation. With each component at expectations or above expectations.

I've played recent triple A titles on it while recording and cpu thermals top out at 77 degrees C, with GPU temps around 65-70 degrees c. At 1440p and 4k. This is with applying my own thermal paste, with the pea method, rather then relying on stock paste. I used Artic Silver 5.

I have also done some 3d rendering with blender set to gpu, and everything works as intended and quick at that.

This is my 4th computer I've built, I'm no where near expert, but I feel pretty comfortable handling components, etc.

I have already tried reseating every component and resetting the Bios via the cmos battery, two or three times to no avail.

The pc turns on and looks as if it's running as intended, cpu fan and LEDs are on, ram LEDs are on, gpu fans are on, the psu fan spins up but then turns off. As I understand it though the psu fan will only spin up if under enough load. No components feel hot or anything. I now even have a little test bench setup on my motherboard box to troubleshoot.

I'm honestly at a loss though and have no clue what's causing this problem. Any help would be appreciated.

 

[Ralston18]

I will put PSU at the top of the culprit list.

Do you have a multimeter?

If so, check the voltages.

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Not a full test as the PSU is not under load.

However, if one or more voltages are out of spec then the PSU has likely failed in some manner.

 

[jhuff247]

I will put PSU at the top of the culprit list.

Do you have a multimeter?

If so, check the voltages.

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Not a full test as the PSU is not under load.

However, if one or more voltages are out of spec then the PSU has likely failed in some manner.

I do not have a multimeter, but I just ordered 1 on amazon for 10 dollars and itll be here friday. Worth a check. The only other thing that I could think of, was that I was using the standard cables that came with the psu, and they were rather stiff. The 24 pin was kinda twisted funny and maybe strained too much at point of attachment onto my motherboard so maybe the cable is messed up? In any case I also ordered a nylon sleeved psu cable set from asiahorse to test a different 24 pin cable. I also need the cables anyway even if I end up returning the power supply and getting a new one. They will also be here friday, so hopefully it will bring me to a solution.

Thank you for the response.

 

[Ralston18]

Cables are also certainly suspect. And a swapping in a new cable is SOP when troubleshooting.

Try to find a way to test the cable(s) elsewhere just as a matter of elimination. I.e., you know that the cables do indeed work.

 

[jhuff247]

Cables are also certainly suspect. And a swapping in a new cable is SOP when troubleshooting.

Try to find a way to test the cable(s) elsewhere just as a matter of elimination. I.e., you know that the cables do indeed work.

K, well I just remembered I had an old pc sitting in my closest with no powersupply in it. So I connected the psu to it and it posted to bios, the harddrive that had windows is no longer in that computer. And the motherboard (asrock extreme 4) is too old for m.2 slots, so sadly I cant put my windows boot drive in there to make it past the BIOS.

The only problem is this computer is running an i7 2700k and a gtx 960, so the power draw is much lower? So this at least tells me it's not a cable problem? But the psu could still be undervolted? But happens to be enough to post this pc?

Edit: I found a windows drive, hooked up to the pc and tried to boot to windows, made it past the motherboard screen and saw a windows symbol, then it shutoff again.

So yeah it's the power supply.

 

[Ralston18]

PSU's can become problematic in many ways.

Just by their inherent nature and design. Then the overall quality of materials and build needs to be considered. And the overall installation process is becoming more complex and cumbersome. Especially when coupled with poor documentation via end user instruction guides/manuals. [Ending possible rant now....]

FYI - if you wish to learn more about PSUs:

https://www.computerhope.com/jargon/p/power-supply.htm

https://www.actpower.com/educational/what-is-a-power-supply-and-how-does-it-work/

(Note: not endorsing any manufacturers or products. You can easily find other similar links with as much PSU technical detail as you desire.)

So even if the PSU is cable of providing the necessary power per se, the voltage(s) need to be correct and within spec. And the output clean and steady.

Then, for the most part, we are constantly demanding more and more power to support activities and things we do on our computers.

And it only takes one little glitch (hardware, software, user error) to bring it all down.

Sometimes the problem becomes identifiable only as a matter of elimination.