my PC suddenly shut off and won't turn on

[sickgeese]

Spec :
I5 4690k
MSI z97 gaming 5
GTX 970
2x4 GB RAM
2x 1TB HDD
1 SSD 240Gb
XFX core pro 850w
Silverstone Strider Plus 600w

I have been using my PC for nearly two years without any problem (no overclocking or tweaking anything). Then one day it won't turn on, no sign of power getting in. Left it overnight to find it able to turn on again in the morning. The next day it won't turn on again after a proper shut down. Tried the paper clip test on the PSU, the fan didn't run. The weird thing is when I return the PSU to the supplier, they tested it and it worked fine.

I still suspected the power supply was the culprit (XFX core pro 850w). So I bought a new PSU, Silverstone Strider Plus 600w. The computer run fine for 2 weeks. But today my computer experience a sudden shut off in middle of use. And it won't turn on again (no boost, no sound, only a blink on mother motherboard and GPU for a fraction of second, then nothing)


What I have tried so far with my pc with 2nd psu.
- Lamp test : no problem with power socket
- Visual hardware check : no sign of any damaged cap or anything on motherboard. Neither the PSU. Every cord and wire is plugged well.
- Resetting CMOS : took out CMOS battery for couple of minutes doesn't help
- Discharging PSU : Pressing power button for 20 seconds while unplugged also doesn't help
- Paper clip test : The PSU fan doesn't run

Note : the 1st and 2nd time of this problem share common event, I'm not sure if they're related to the problem : they got a power outage a day before. Could both PSU blew up by that? But both of them still run fine till the day after.

I want to blame the PSU again but since this is a new one and the circumstances are not decisive (for example, the PC able to run after experienced power outage for some time, or I might did the paper clip test wrong. I'm sure of anything now.

What do you think? is it the motherboard or PSU? what else could be the problem? Please advise.

Thank you in advance for your opinions.

 

[sickgeese]

Found that it was both. Might be other components too.
RMA the 2nd PSU and sure as hell it was dead.
Plugged the new PSU in. There was light on fan, motherboard for half a second then nothing.
Could check that the SSD is ok. Unfortunately I have no mean to check the hdd, GPU and CPU.

What could cause such catastrophic failure? Is it power surge? But can PSU and mainboard still operate for another day after suffered from power surge that come from exploded transformer on the street? Or does 600w PSU can't handle the load from my system?

 

[shag00]

A bad PSU can terminally damage other parts of your system including the motherboard and PCI components including the GPU. My first step would be to disconnect everything and see if the system runs just using the motherboard. One of your new PSUs must work...

 

[sickgeese]

My apology. I might wrote too long. Let's put it more simply

One day, a transformer blew up in the street caused blackout. I still able to use it for another day before it won't turn on. 1st PSU broke. Return it, but the guy at the shop said it's ok. I decided to return it anyway.

Next month. Same thing happened, a boom and blackout, able to use my computer for one more day. Then it crashed and won't turn on. This time 2nd PSU dead, motherboard dead. I found out that the rest of components is ok.

The question is :
1. what had hit me? Power surge?
2. If it was a power surge, is it normal for PC to able to keep running for sometimes before failing completely like mine?
3. Anything else could be the cause?
4. Do I need a UPS? or surge protector (but my room doesn't have a ground socket on the wall, are they still useful?)