Question Dead PSU? Motherboard? CPU? All three???

[Roninson]

My main machine, which was running fine until recently, is now dead - no POST, no debug LEDs, nada - and I've been attempting to zero in on the faulty problem. I've read through and tried the "No POST", "system won't boot", and "no video output" checklist but to no avail.

Specs:

• i9-10900k w/ EK 240mm AIO
• MSI z490 Gaming EDGE Wifi
• Thermaltake ToughPower GF1 850w PSU
• G.Skill Ripjaws 16GB DDR4 (x4)
• EVGA FTW 3090
• Samsung 9800 Pro M.2
• NZXT H510 case

First guess was a bad PSU. I order a new one, install it and... nothing. I ordered a PSU tester and once I received it, checked both PSUs, which both seem to check out. So, now, thinking its most likely the motherboard, I breadboard the machine to confirm it. Again, it doesn't POST or light up the debug LEDs. I even try each of DDR sticks individually to rule out the memory. I also try different power cables to rule out those as well. No different results.

Thinking its now the motherboard, I order a new motherboard (thankfully found a deal on the same one I had). I receive it, and immediate try breadboard first -- just CPU, mem stick & PSU. Again, nothing. I remove the CPU from the breadboard setup, in hopes to see the motherboard debug LEDs light up, warning there's an issue with CPU. Again, nothing.

Now, I'm thinking it might be the CPU? But I'm not entirely confident in that - particularly when removing the CPU didn't fire up the debug LEDs.

Before spending more money, I'm now going to see if I can borrow a co-worker's extra machine to hookup the PSUs - confirm they are working as expected.

But overall, I'm concerned I'm chasing the problem - perhaps damaging good components with faulty ones.

I might be too close to the problems now, so any perspective/recommendations would be welcomed.

 

[Darkbreeze]

Have you tried booting with the graphics card completely removed? Not just disconnected from power and display cable, but actually out of the board?

Have you tried a wall outlet that is on a completely different circuit? Or checked the outlet with a tester to ensure there isn't a fundamental problem there? If using a power strip or "surge protector", eliminate that and plug directly into the wall.

I'd also remove any storage devices including M.2 drives, just to see if perhaps there is a problem like an internal short on something that is keeping protections triggered on the board or PSU.

And while bread boarding are you jumping the power pins manually or trying to use the switch from the case to power on the PSU and board?

 

[Roninson]

Have you tried booting with the graphics card completely removed? Not just disconnected from power and display cable, but actually out of the board?

Have you tried a wall outlet that is on a completely different circuit? Or checked the outlet with a tester to ensure there isn't a fundamental problem there? If using a power strip or "surge protector", eliminate that and plug directly into the wall.

I'd also remove any storage devices including M.2 drives, just to see if perhaps there is a problem like an internal short on something that is keeping protections triggered on the board or PSU.

And while bread boarding are you jumping the power pins manually or trying to use the switch from the case to power on the PSU and board?

Hey Darkbreeze- Thanks for the quick reply.

Yep, I'm down to just CPU, one stick of mem and the PSU -- no GPU or M.2 -- and all out of the case and with the motherboard on an anti-static mat. I'm connected directly to a wall outlet -- though I don't have a tester to confirm voltage, I've used it for other electronics recently, which worked fine.

I'm jumping the power pins manually, with a screwdriver. Though, I've also tried the front panel leads/switch from the case as well. Neither seem to result in anything different.

 

[Darkbreeze]

Well, doesn't seem TOO complicated then.

Two different power supplies, same result.

Two different motherboards, same result.

Tried all four DIMMs individually in the A2 slot, same result.

No drives or other attached hardware, no change.

Nothing left but the CPU, and while that is an incredibly uncommon thing to have happen, as CPUs don't just generally "go bad" without something like user caused damage, power surge/lightning strike etc. happening, it DOES occasionally happen.

Although I WILL say this. Since I know that is it incredibly unlikely that you found a new Z490 board unless it was supposedly "new old stock" since those boards have been out of production for some time now, I might not 100% rule out the board either.

Where did you buy the second board from and was it supposedly new, or used?

Just for grins, might also want to try a different power cable to the PSU if you haven't already. And make certain that outlet isn't dead by testing it with a lamp or something.

 

[Roninson]

Well, doesn't seem TOO complicated then.

Two different power supplies, same result.

Two different motherboards, same result.

Tried all four DIMMs individually in the A2 slot, same result.

No drives or other attached hardware, no change.

Nothing left but the CPU, and while that is an incredibly uncommon thing to have happen, as CPUs don't just generally "go bad" without something like user caused damage, power surge/lightning strike etc. happening, it DOES occasionally happen.

Although I WILL say this. Since I know that is it incredibly unlikely that you found a new Z490 board unless it was supposedly "new old stock" since those boards have been out of production for some time now, I might not 100% rule out the board either.

Where did you buy the second board from and was it supposedly new, or used?

Just for grins, might also want to try a different power cable to the PSU if you haven't already. And make certain that outlet isn't dead by testing it with a lamp or something.

Roger that. The Z490 board is refurbished from NewEgg - but yeah, I'm still suspect of it because the debug LEDs never fire up (but not on my original either). From what I understand, the LEDs on Z490 board should light up when there's an issue with the CPU or other components. So I'm unsure why I'm not seeing that, even with a faulty CPU -- unless I'm misunderstanding how those debug LEDs work.

Outlet/Plug: I thought the same, and did try another PSU power cable as well - no difference there. The outlet I'm using works for other items (charged my laptop on it last night). And to make sure, I just tried a lamp now too - which lit up.

Yeah, so most likely the CPU at this point. Just becoming a costly chase of tracking down the problem.

 

[Darkbreeze]

Here is your low cost solution finder. 33 bucks to determine if it's the CPU seems worthwhile, and you can always resell the CPU to recoup your investment OR put it with one of the motherboards if it turns out they are ok and sell it as a bundle. Or keep them for troubleshooting purposes in the future. At least this should tell you something and is less expensive than any other option.

https://pcpartpicker.com/product/FpXYcf/intel-celeron-g5925-36-ghz-dual-core-processor-bx80701g5925

DO you know when, exactly, you purchased that CPU? Because Intel CPUs have a three year warranty and that CPU was released in April of 2020 which would mean the warranty was expired but it depends on when YOU purchased yours. Assuming of course that you bought it new and not used.

 

[Roninson]

Here is your low cost solution finder. 33 bucks to determine if it's the CPU seems worthwhile, and you can always resell the CPU to recoup your investment OR put it with one of the motherboards if it turns out they are ok and sell it as a bundle. Or keep them for troubleshooting purposes in the future. At least this should tell you something and is less expensive than any other option.

https://pcpartpicker.com/product/FpXYcf/intel-celeron-g5925-36-ghz-dual-core-processor-bx80701g5925

DO you know when, exactly, you purchased that CPU? Because Intel CPUs have a three year warranty and that CPU was released in April of 2020 which would mean the warranty was expired but it depends on when YOU purchased yours. Assuming of course that you bought it new and not used.

Good call on the cheap CPU! I have a friend who's looking to build a machine for his son; I could gift it to him if he hasn't built a machine already. Otherwise, like you said, good troubleshooting kit.

CPU purchase; Looking at the emails from when I was building the machine; it looks like I purchased most components back in November & Dec. 2020 (and yep, CPU was new).

Downside is for some reason, I can't locate the receipt/email for the CPU itself. 🙁

 

[Darkbreeze]

Well, that sucks, because it would still be under warranty if you can find any kind of record or reciept of your purchase. Invoice, receipt, credit card statement, probably about anything would work. You might even be able to contact whoever you bought it through, or log in to their website, and get a copy of it.

 

[Roninson]

Roger that - started down that path this morning.

Thanks for all your suggestions and help! Finally have some sanity around this!

 

[Darkbreeze]