Question VERY strange intermittent booting issue (I suspect mobo)

[picklebusGQ]

To preface this inquiry, I know my way around PCs and PC parts. I'm typically that one friend that educates others about their hardware, but I ran into a very strange issue that I've never heard of before in my life. I searched the entire internet over, and not one single post on any forum out there was even remotely similar to what I'm experiencing.

I woke up one morning recently to find out my PC no longer boots, and I was very angry. I built my PC in more fortunate times, and currently, I am not in those fortunate times and cannot afford to replace anything. I went days thinking something in my case bricked, and I suspected it was my PSU because of my past issues with PSUs (plural) bricking. It was similar, my PC just wasn't turning on. I was busy working, so I didn't sit down and try to figure out the problem for a couple days, but when I did, my brain was in a haze. I was just ticked off that reseating everything, testing all the outlets, testing my PC on other outlets etc. I was convinced my PSU took a dump, so I went and bought a new one... Long story short there, it didn't fire up my PC, and I returned it seeing as I couldn't honestly afford it anyhow, and needed my money back.

One day my wife was on her PC and feeling sorry and told me she wished my PC would work so she could feel less guilty for using hers. (lol) I sarcastically said, "well too bad wishing doesn't fix my PC" as I click the power button and watch this dumb thing fire up after days of not responding.

?????

I tried to fire it up the next day, and same thing, wouldn't boot. I decided to run a few tests, I grabbed my multimeter to make sure my outlets were performing up to snuff, which they were. I ran DC to check if the CMOS battery was at full health, and it was. I checked the power cord for integrity, and all signs were clear, there was no issue with the power cord. Intermittent booting continued, but it was more consistent. It fired up more often than not. Sometimes I had to flip the power supply to 0 and back to 1, and then try again and it would fire up.

Today I got home, and it was completely unresponsive again. I came up with the bright idea "let's paperclip test my PSU to build up some energy, then plug it into the port. Sure enough, it's almost like jump starting a car, it started up with no problem.

When my PC is on, it's not buggy, it doesn't act strange. It runs perfectly fine. At this point I'm assuming there's a problem with the motherboard, but I wanted to see if there was anyone who has more knowledge on the topic of motherboards in here who can confirm or bust this myth.

Another important thing to note is my wife's PC also didn't start for a while on the same day, so we assumed a power surge bricked our PCs. We were both mad as heck, but hers started up later that evening and never had a problem since. Mine on the other hand has been very intermittent.

SPECS:

Mobo: B450-A Pro / Chipset AMD
CPU: AMD Ryzen 7 1700
GPU: Nvidia Geforce GTX 1080
PSU: EVGA 600W Bronze
Memory: 16GB DDR4 RAM Ballistix
Hard Drive: Samsung SSD 860 EVO 1TB

 

[RealBeast]

First, don't work on your PC when angry -- you will tend to make mistakes. Wait until you feel calm so you can think clearly.

Since you passed the paperclip test, the next test would be to pull the two small wires to the power on pins in the lower corner of the board and then just touch the two motherboard power on pins simultaneously for a second or two with a piece of conductive metal -- I use a phillips head screwdriver. If it starts up either the power switch or the wires to it are damaged. Seen it many times.

If that fails, I would pull everything out of the case (gently and carefully) and do a desktop build on a sheet of cardboard to insure that there are no unwanted grounds, which is also not terribly uncommon. If this works then carefully reinstall everything. If not, it is far easier to test component by component.

I suspect that it will relate the switch/wires or a ground though.

And when things improve financially (I hope soon) consider using a UPS on your machines. I like APC with software that shuts the machine down when battery life is down to 5 minutes or whatever.

Let me know how it goes.