PC will not start after random power down.

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Hi All,

My PC first booted and ran with no problems, during normal use the PC turned off/black screened. Seemed to attempt a reboot automatically giving the code bF. After reading though a couple of posts about similar issues I went about reseating RAM, taking out the GPU, giving it a bit of a clean (wasn’t that bad tbh I do this every other month) and clearing CMOS. It ran through a few codes and wound up on bF again. I was going to try 1 RAM at a time, but now it won’t even attempt to boot. I would say power supply, but I do have a light still on the liquid cooler. Any ideas?


Motherboard – ASRock x99


This PC hasn’t been moved/any thing new fitted/changed in the past few months (which was a GPU) and other than that hasn’t been changed since build a few years ago.

Thanks in advance,

James
 
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'I was going to try 1 RAM at a time, but now it won’t even attempt to boot.' I did try this and that’s when nothing started to boot (Admittedly thinking about it I did not remove the wifi card, but I don’t think that would cause the problem). I did not cycle though the sticks as I should have, but I needed to go to work. Ill try another stick when I get home.
 
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From memory its:

Mobo: Asrock x99 Extreme6
Processor: i7-5930K
RAM: Avexir 4x4GB
Power Supply: SuperFlower 750W
SSDs: 2 SSDs connected one a Samsung 850 and I cant remember the other
WifiCard: Cant remember this one at all sorry somthing cheap when moving house over a year ago when went from hard wired to wireless during the moving in period (back to hard wired now so dont really need it)

The GPU is disconnected so shouldnt chnage anything.

Thanks for that trick on testing the PSU, I'll try that later
 
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From my understanding of a 7 segment display the top segment was not lit which would be the difference between a b and a 6 and therefore is a b. But any sugestion helps at the moment. I'm still at work so will try all of this when I get home.
 
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From my understanding of a 7 segment display the top segment was not lit which would be the difference between a b and a 6 and therefore is a b. But any sugestion helps at the moment. I'm still at work so will try all of this when I get home.

The fact of the matter is. Even if the CPU or ram was dead it would still power on, fans would spin, LEDs would light up etc, it just wouldn't post, I'd be first looking at your psu, especially as you say it's totally lifeless except for an led on the cooler which can easily be running off the 5v line of the PSU which in turn maybe fine.

You have different 3.3v, 5v, 12v and ground lines all coming out of the PSU, it's usually the 12v lines that go first, the fact you said it randomly powered down says to me it's the PSU, it just lasted a few seconds afterwards whilst the caps in the PSU drained.
 
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1. Check that the wires from the PSU are properly plugged into the motherboard, nothing is loose. See if both 24-pin mobo plug and 4/8-pin CPU plug are both connected and secure.
2. It may be not the RAM stick but the RAM slot or both. Try it cycling through the RAM modules but also through the sockets they plug into.
 
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Hi All,

Thanks for the help so far, just got home and started testing. The PSU seems good, thanks EsaT for that test method, when disconneded from everything and the jumper in place it started up. Knowing the PSU is good the RAM was the next bet, I tried each individual stick and nothing. I have tried the PWR button on the motherboad if there was a problem with the case button. All power cables from the PSU to the motherboard have been reseated. Anymore ideas? Im thinking a motherboard problem now...
 
Soldato
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Hi All,

Thanks for the help so far, just got home and started testing. The PSU seems good, thanks EsaT for that test method, when disconneded from everything and the jumper in place it started up. Knowing the PSU is good the RAM was the next bet, I tried each individual stick and nothing. I have tried the PWR button on the motherboad if there was a problem with the case button. All power cables from the PSU to the motherboard have been reseated. Anymore ideas? Im thinking a motherboard problem now...

If you remove the ram and try and switch on without the ram installed, does it power up ? if not, id say your motherboard has bitten the bullet.
 
Soldato
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The PSU seems good, thanks EsaT for that test method, when disconneded from everything and the jumper in place it started up.

I have tried the PWR button on the motherboad if there was a problem with the case button.
Only 100% sure thing jumpstarting PSU tells, is that it's not completely dead.
100% knowing actual state would need measuring voltages and also ripple.
With preferably some load.

Also you need to detach power/reset buttons of the case to make sure there's no fault in them.
Failed and shorting switch can make motherboard's power control electronics not know what to do.
Actually motherboard's switch is in parallel with that and could also cause problem.
But that's very unlikely because that switch should be basically in factory new condition and without any wear.
 
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