Question PSU turns on but no POST. Reset button starts it ?

ebj423

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Nov 14, 2018
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Hi! In the normal start up process, my pc's power led will turn on, the hdd led lamp will flash brightly for a moment and then beeps once and you know everything is starting up fine. But recently, it will just flash dimly and then nothing, no beep to show it is posting. Luckily, I discovered that the reset button will initiate the post (the lamp flashes brightly and beeps and everything is fine, but you have to press the reset button, tiringly, a lot of times.

I checked the voltages, (+3.3v) 3.38v, (+5v) 5.19v, (+12) 12.15v, (-12v) -11.8v, (ps_on) 4.55v off / 0v on and running, (pwr_ok) 0v off / 5.18v on and running and (+5sb) 5.22v off / 5.18 on / 5.14 running. Both fans and all pheripherals are on, even the lan port is flashing. I checked the ram, all 4 x 4gb are fine. Both hdd's are fine, too. That only leaves me with the motherboard as suspect. But I'm at a loss where to start.

Can someone please tell me if I missed something or where to troubleshoot if it's the motherboard? I also tried isolating the board from the chassis in case of a short but it's just the same. I also swapped my psu twice. Thank you.

OS - win7 ultimate
cpu - I3-3240
gpu - internal
mb - B75M-Plus
ram - 2x4gb hyperx, 2x4gb elite
bios - updated to latest a few years ago
drivers - updated to latest
case - skywalker
 

ebj423

Reputable
Nov 14, 2018
4
0
4,510
0
Using the pc at the moment so the name is covered. Its a generic one but dependable. I did swap it out with another generic Esgaming atx-750w and a branded Antec hcg850 bronze w/ the same result. Right now trying to trace the power ok signal but boardviewer schematic is a deadend.
 

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