PC trying to boot, turning off, turning on...

devilzrox

devilzrox

devilzrox

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17 Apr 2015
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Just wondered if anyone could shed any light on what might have happened here...

So I built a rig recently:

Fractal Design Arc Mini R2 case
Asus H97M-E Mobo
Intel i7-4790K using stock cooler
2 x 4GB Crucial Ballistix Sport DDR-3 1600 memory
Corsair CX500M PSU
120 GB SSD
2 x 120 intake fans (front)
1 x 120 exhaust fan (rear)
2 x 140 exhaust fan (top)

It ran perfectly for nearly a month, using integrated graphics and then I bought a GPU and fitted that:

EVGA GTX970 Superclocked (Blower style)

Again everything worked ok for about a week. However I was worried the PSU wasn't good enough, so I upgraded to:

Coolermaster VS550 PSU

Changing a semi-modular PSU to another semi-modular PSU was the biggest task since the initial build. I was careful to use ESD protection (as I did using the initial build, and successfully removed the old PSU and fitted the new one. I concentrated harder on cable management this time round, and used cable ties, perhaps too tightly.

When the whole rig was back together, I booted up and for a few minutes all seemed as usual.

Then something strange happened. It shut down.

When I pressed the power button again, the fans started for a second, then went quiet. This process repeated about 8 times, without me needing to press the power button, then finally died.

I couldn't even get as far as BIOS. And as there is no internal speaker on that case, I didn't know what POST was doing.

Opened case up, tried again, same result. Removed PSU completely, tried old PSU. Same result.

Took all cable ties off, removed SSD, disconnected fans, removed GPU.

Got as far as Asus splash screen, but with strange lines/pixellation all over screen. Died again.

Put new PSU back in. Tried again. This time got all the way to boot menu with no screen weirdness. BIOS readings on CPU seemed fine, with good temp/fan readings. Same with memory.

Re-connected SSD, GPU and fans, testing boot between each one. All fine. Now getting to full OS with no problems.

Re-built rig properly, with cable management, but left really loose this time (cable management behind mobo is quite restrictive on this case, so not the easiest thing to do). Booted to OS fine.

Left running for a couple of hours, ran Unigine Heaven for 15 mins solid. All temps seemed fine on HWInfo.

It's been 12 hours now. Not doing anything intensive on it, left overnight, have restarted a few times manually to see if any anomalies. None.

So what happened? And I wonder if it could happen again?
 
Yes. The pixellation was there when it was just the PSU, Mobo, Ram and CPU. No Discrete GPU or Boot Drive. Then it went, and I began assembling the rest piece by piece, testing boot each time.
 
Weird. Thinking about it, have you tried a different monitor/monitor cable? I've had loose monitor cables do this from time to time if they aren't plugged in quite securely enough.
 
Yep, same HDMI cable I had been using in both the onboard HDMI for about a month, then in the HDMI on the GPU for the past week.

It is odd. I'm no expert but I've gone through all it could have been. Some people have told me memory, but there were no faults either side of this weird "window". The computer has run like a tank before, and seems to be even more tank-like now (with the gold PSU).

Even if it had been an overtightened cable tie, then surely the problem would have rectified immediately afterwards? Nope. About a dozen more times of the CPU cooler fan starting, stopping, pausing, starting, stopping for good. Both the old and new PSU (with their own cables, not mismatched) wired directly to the mobo from OUTSIDE the case, so cables running direct and not behind the mobo made NO difference. And just when I was about to remove the CPU cooler, with the intention of removing the mobo completely, I tried one more time. It booted like there had never been a problem, and continues to.

I have a theory of my own, and I've opened it up since to check, but I wonder if there's anything to it... I checked the front panel headers to make sure all of them were in place. They were. I wondered if, say, the power switch header might have come loose and kept shorting, dislodged by removing the heavy cables of the old PSU? But, as I say, they were all in fine.
 
Its quite possible your theory is right.

However not noticing this at the time means you will not be able to tell.

As long as the PC is running stable now i wouldn't worry about it.

However the header would not cause pixelating or display issues, so that doesnt quite add up.

I would say it could be either a motherboard of memory issue personally. But if the unit is ok and stable now I would not bother wasting more time on it until it has more issues.
 
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