[SOLVED] PC suddenly now only powers on (lights/fans) for an instant, then turns off. No POST code, no beeps. PSU tests fine. Mobo dead?

[keleryn]

My desktop is custom built, late 2013. I upgraded the GPU and PSU in late 2015. Worked great until it suddenly started not fully powering on a couple weeks ago. The lights and fans come on for an instant, then it shuts right back down.

Removed every component except mobo, CPU, and PSU to test, and it does the same thing.

I got a PSU tester and it shows that it's working fine. Got a POST tester, but it powers down before a code appears. No beep code either.

Any other thing I should check before accepting that I need a new mobo? Really can't afford to replace right now since I'd likely need a newer CPU and RAM as well unless I could find an older board.

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Mobo: ASRock Z87 Pro 4

CPU: Intel Core i5 4670k

PSU: EVGA Supernova NEX750G

 

[Darkbreeze]

Removed every component except mobo, CPU, and PSU to test, and it does the same thing.

You need memory and a CPU cooler as well, to test anything. System won't do anything in most cases without both memory and a CPU cooler installed. Assuming you DID have those things installed, what KIND of PSU tester are we talking about?

One that actually tests the 12v, 5v and 3v rails and reports on the health of the power supply, or one that simply tests to see if the fan comes on and isn't much different than using a paper clip to jump the wires in the connector?

 

[keleryn]

You need memory and a CPU cooler as well... what KIND of PSU tester are we talking about?

Yeah, I left the RAM and cooler in as well. Just removed everything non-essential to narrow down what was failing. The cooler fan starts up fine, for the instant that the machine is on.

Yes, I am using a PSU tester that shows the various rails. Just has little LEDs that light up for each rail.

 

[Darkbreeze]

Well, if the PSU is good, and this began in a system that was working fine, then given the age of the motherboard I'd be incredibly surprised if it was anything other than the motherboard assuming that you also eliminated the graphics card and are using the motherboard video output to attempt to POST.

 

[keleryn]

Well, if the PSU is good, and this began in a system that was working fine, ... assuming that you also eliminated the graphics card

Yes, yes, and yes.

Alright then, I guess I'll just have to accept that the mobo kicked the bucket.

Today I reset the CMOS with the jumper and replaced the battery, reseated the CPU and cooler, and tried starting it all out of the case with the mobo on cardboard, but nothing worked.

Basically tried everything listed in all the motherboard troubleshooting guides I found except swapping in other components or trying my components in another machine, since I don't have any extra parts available.

I can't really afford a new CPU/RAM right now since mine are apparently still working fine; do you have any suggestions on a good motherboard that would still be compatible with DDR3 RAM and an i5 4670k?

 

[Darkbreeze]

A new, or good used, Z board for Haswell era CPUs is going to cost you a large chunk of what it would cost to simply upgrade. My advice would be, don't waste the money on a used board that may also kick the bucket in a week or month, and don't waste the money on a "New old stock" board that gives you the same performance that you have now, when it could go towards an upgrade, and besides which you'd pay way too much for it because the only reason people hang onto those old generation boards in new condition is to bludgeon somebody with the cost of them later. They know that some people will pay way more than the board is worth to not have to pay what it costs to upgrade the whole platform.

Personally, I think the money is much better spent towards a new platform.

PCPartPicker Part List

CPU: AMD Ryzen 5 3600 3.6 GHz 6-Core Processor ($159.99 @ Amazon)
Motherboard: ASRock B450 Pro4 ATX AM4 Motherboard ($89.99 @ Newegg)
Memory: G.Skill Ripjaws V 16 GB (2 x 8 GB) DDR4-3000 CL16 Memory ($56.99 @ Newegg)
Total: $306.97
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2020-08-01 02:21 EDT-0400


But if you are willing to take your chances with a used board, then there are plenty of options to choose from on a variety of Z97 (I'd go with that rather than Z87) motherboards on Ebay but most of the ones worth entertaining are about half the cost of that new build I posted above.

 

[keleryn]

Thank you for the suggestion. Ended up going with the B550 for a bit more. Made it out at ~$353 at the local Microcenter. Just set it all up, works beautifully.

 

[Darkbreeze]

Nice man! Probably the better choice, but was trying to keep the price down as much as possible since you said finances were an issue at the moment but glad you got it fixed AND that the fix was an update that undoubtedly leaves you in a much better place than you would have been even had you been able to get the old platform going. Now, maybe if you desire, you can sell off the old parts to recoup some of your investment OR locate a used motherboard and either sell it off as a working bundle or use it as a backup system at some point. Either way, glad to hear you are up and running and good luck to you.