Question Asrock Z370 Extreme4 no longer powers on

[almiki99]

My build has been working fine for about 5 years, and suddenly it won't turn on. I've removed everything but the bare minimum components and I'm still seeing the problem.

• Asrock Z370 Extreme4
• i7 8700K
• EVGA SuperNOVA 650 G+ PSU
• 1 stick of RAM
• GPU, hard drives, and fans all disconnected

When I switch on the PSU, some white LEDs (e.g. the backlights for logos and stuff) briefly flash on but then remain off. If I connect ethernet, the ethernet port lights blink normally.

When I press the PC power button, the PSU fan twitches but doesn't spin. There are no beeps or LEDs on the motherboard. If ethernet is plugged in, the ethernet port lights stop blinking. I don't see any video from the motherboard's HDMI out. I know power is drawn for a moment because the lights in the room dim a bit (normal), and the power strip has a little indicator light that goes on for a second but then turns off. Pressing the PC power button again has no effect until I switch the PSU off/on.

I have "tested" the PSU with its included jumper connector thing, and the PSU fan runs, so the PSU is at least not totally dead.

So I'm wondering what the most likely problem is. I'm guessing it's probably either the PSU or motherboard? Is there enough info here to narrow it down? Should I just buy a new PSU and hope for the best, or is that premature? Unfortunately this was my first and only PC build so I don't have spare parts around to test with.

 

[baboma]

Take MB & PSU out of case for bench test. Take ESD precaution.

PSU pin-out
https://goo.gl/search?pc+power+supply+pinout

PSU test w/ multimeter

View: https://youtu.be/YixrxhLLv8o

Clear CMOS. https://download.asrock.com/Manual/Z370 Extreme4.pdf

Test RAM by trying one stick at a time (assuming more than one). It's not likely that both sticks would fail at same time. So if both has same issue, RAM isn't cause.

Assuming no overclock, CPU is least likely to fail. If you reach this point, LGA 1151 motherboard replacement is next. Used boards on eBay start at around ~$20 (watch out for proprietary boards).

Alternatively, upgrade.

 

[almiki99]

Take MB & PSU out of case for bench test. Take ESD precaution.

PSU pin-out
https://goo.gl/search?pc+power+supply+pinout

PSU test w/ multimeter

View: https://youtu.be/YixrxhLLv8o

Clear CMOS. https://download.asrock.com/Manual/Z370 Extreme4.pdf

Test RAM by trying one stick at a time (assuming more than one). It's not likely that both sticks would fail at same time. So if both has same issue, RAM isn't cause.

Assuming no overclock, CPU is least likely to fail. If you reach this point, LGA 1151 motherboard replacement is next. Used boards on eBay start at around ~$20 (watch out for proprietary boards).

Alternatively, upgrade.

Thanks for the helpful reply. I don't have a multimeter, but I had a hunch (and hope) that the issue was simply the power supply. So I replaced it with a new Corsair RM750e, and that fixed the problem. Now to try to get the EVGA PSU replaced under warranty so that I'll at least have a spare now.