PC shuts down randomly, power light flickers (not blinks in a pattern) when turned black on

[Hihikar]

Firstly I want to sincerely apologize if I misplaced this thread for I am a complete newb here, but I am in a dire need of help.

My PC shuts off completely randomly (not heat related it seems). When I try to turn it back on, the power LED sometimes first starts flickering with ticking noise, and then after a few seconds of flickering it just starts, comes to life. Like something is forcing it to turn on and it finally does. Sometimes it works for hours straight, sometimes it shuts off every 5 minutes. Good thing Chrome keeps the text I wrote because it shut off four times (I am changing the number accordingly throughout every shutdown) while I was writing this text.

The interesting thing comes next. It was happening some months ago. I brought it to a repair shop and they couldn't find out what it is (weirdly it worked there), so they returned it to me with no charge. When I put it up at home, it was mysteriously not shutting down anymore. After some short time it started again, but rarely.
Then, it stopped completely, for a few months - I have already forgotten about this issue. I was playing games on blistering summer heats and CPU temp didn't go over 50. It was all ok - UNTIL I took out the graphics card, to bring it to my friend, so we could test something on his machine. When I brought it back home and installed it back again, the shutting down and flickering thing started all over again! If it were capacitors (I changed them once), what's with the long pause/absence of the problem?

I feel that it maybe has something to do with some contacts in the motherboard. I have checked them already but I can't figure out what it is. Can you please direct me what kind of loose contact could cause this kind of shutdowns, and the weird power flicker?

The reason why I am in such a deep trouble is because I am supposed to have some kind of a skype work interview, for a job that I'm supposed to do on this particular PC. If this doesn't get better and this dull metal box keeps shutting off, I'm gonna get fired pretty soon.

I apologize again for the possible placement mistakes and thanks in advance!

 

[Hihikar]

Bump, please?

 

[jdlech]

This might be a tough one.
From what you wrote, I'm assuming this is a mechanical failure - moving the computer around affects the problem. So, we're probably looking for a loose connection - as you already suspect. But this could be anything, anywhere. It could be a broken solder joint - on a board with thousands of solder joints. It could be inside the PSU - somewhere you'll never see. Just the vibration of a fan or the flexing caused by simple heating/cooling could break the connection or you could bash it with a hammer and never get it to break connection.

Perhaps if you stripped it down to the barest minimum. On board graphics, 1 hard drive, 1 memory stick, keyboard and mouse. Nothing else attached. Power it up and see if the problem persists. If so, then you know it's not the peripherals.
Then swap the power supply with a known good one. If the problem remains - then it's probably the motherboard itself.

The problem is going to be: every time you move it around, you could make the problem disappear for months, or make it worse; you'll never know which.

 

[Hihikar]

Thank you for the reply.
The motherboard and the PSU are both old, so this issue doesn't really surprise. When the connection is good, they both show as working correctly. The main problem is that I can't afford new parts, as I need to get that job so I can afford to change them - damn absurd.

However it is exactly as you wrote. Moving it around does affect the problem. I guess there is not a lot I can do, but you helped me be pretty sure that it was a loose connection or some kind of a mechanical failure and I wasn't overlooking something stupid.

I really appreciate you took your time to read my post. In an ideal situation I will change both the motherboard and the PSU, as I can't see anything else being the problem. I don't have an onboard graphics card on this motherboard, but I am rather sure it is not causing the shutdowns.