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HELP: Mobo or CPU issue?

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Blx68

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#1
Hi guys, this is kinda long as I want to be as thorough as I can but I'll also try and keep it brief. So I started having issues with my computer blue screening alot and then eventually rebooting as soon as it passed the bios. I came to the conclusion that the os (win 10) was corrupted and I thought I'd do a clean install.

When I attempted to sort it out, the pc seemed to power up but nothing was displaying on the screen and my keyboard wouldn't light up as it usually would indicating it was functioning. I decided to take it apart, clean, thoroughly reassemble and try again, same thing and this time the back fan wasn't working. I tried it on a different monitors, using different display cables and connecting directly to the mobo rather than the gpu but to no avail. So I tried to test the psu, it blew and a bought a new one. Same issues.

At this point I figured it was definitely the mobo as in my eyes the USB ports and the display ports weren't working but I hadn't considered the cpu. So I bought a refurbished version of the same mobo I have.

I just finished installing it today and some of the same issues are occurring. All of the fans inside are spinning including the case fan that wasn't before but still nothing is displaying on the screen and the keyboard isn't coming on or functioning either. So now I'm at a loss. I think the problem is with the cpu but does that really affect whether the USB ports are function so that the keyboard isn't working? Or is the issue with the mobo again or both? Any response would be greatly appreciated.

My specs:

OS: Win 10 home
MOBO: GIGABYTE Z97X-GAMING 3 INTEL Z97
CPU: Intel I5 4670
GPU: Gainward GeForce GTX 770
RAM: HyperX Fury 16gb (4x4gb) ddr3
PSU: EVGA 750 GQ
1x 250 gb ssd
1x 2TB sshd
1x cpu fan
 

Blx68

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Aug 29, 2018
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#3
Hi thanks for replying.
Hello

It is a possibility that your psu is not working correctly.. How old is this psu?

@phillpower2 @Bruce
Hi, thanks for responding. It's brand new I literally just got it as the old one blew. I tested it using an electronic psu tester and it seems fine.

As an update. I have removed nearly all connections from the mobo. The only thing connected to it are the psu, the psu fan, the tiny cables powering the on/off and reset buttons on the front panel and a couple of the ram sticks of which I've tried taking a couple out. When powered up, the exact thing happens which is nothing will come on the screen and the pc will restart after about 6-8 seconds. I'd attributed this to the os being corrupted so that the pc was failing to start properly but the drives aren't even connected.
 

Blx68

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#5
Ok..when you say the old psu blew up,could you describe exactly what happened.
I was testing all the cables coming from the psu using an electronic psu tester and stupidly put the 6 pin in the 8 pin connection without thinking. A heard a small pop and the psu stopped working. It wasn't connected to anything at the time, I'd taken it out of the pc case.
 

Bruce

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#6
first up. what is the age of the PC and any chance it is still under either manufacturers or extended warranty?
next, have you removed, cleaned, re-pasted and reseated the CPU?
are all the parts the same age? (any swaps, upgrades, over the years)

CPU's tend to be the least likely components that fail, so I'd leave testing that one till last.
with the CPU being 4th gen, I'm guessing the mobo is about 4-5 years old?

with the OS being re-installed, and all things disconnedcted from the mobo that are necessary, that sort of puts the spotlight on the mobo for me.
 

Blx68

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Aug 29, 2018
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#7
first up. what is the age of the PC and any chance it is still under either manufacturers or extended warranty?
next, have you removed, cleaned, re-pasted and reseated the CPU?
are all the parts the same age? (any swaps, upgrades, over the years)

CPU's tend to be the least likely components that fail, so I'd leave testing that one till last.
with the CPU being 4th gen, I'm guessing the mobo is about 4-5 years old?

with the OS being re-installed, and all things disconnedcted from the mobo that are necessary, that sort of puts the spotlight on the mobo for me.
Thanks for responding. I built it around 4 years ago and all parts were new. As far as I'm aware nothing is still under warranty.

The psu I only bought last week brand new is under warranty. The mobo that's currently in the pc and replaced the original one just arrived today, was refurbished and fully tested according to the company I bought it from. The ssd was replaced a couple of years ago and a couple more ram sticks were added 2 years ago also(was 2x 4gb and added another 2x 4gb of the exact same model).

I cleaned the cpu, reapplied the thermal paste and reseated it a last week on the prev motherboard and again today with the new one.

I also haven't had a chance to reinstall the os as I haven't got a backup pc at home to do so but I was hoping to do so after I got the rest of it running properly.
 

DOUGIE

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Jun 1, 2017
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#8
I was testing all the cables coming from the psu using an electronic psu tester and stupidly put the 6 pin in the 8 pin connection without thinking. A heard a small pop and the psu stopped working. It wasn't connected to anything at the time, I'd taken it out of the pc case.
I have popped a PSU. Normally only the Fuse blows. I bought a fuse, soldered the 2 wires on the fuse end caps, and good to go again.
I bought the new PSU, and didn't look, and was set to 110 volts, and popped the fuse.
 

vger

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Jul 21, 2016
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#9
In my experience,if a psu goes pop,that usually seeds a feed back/surge to the mobo and then the mobo is toast.. I hope this is not the case here.
 
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gus

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#10
I have seen PSU's fail and take out almost everything connected to it as well. Not saying this is your problem but you will need to test all other components as well.
 

Bruce

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#13
I was testing all the cables coming from the psu using an electronic psu tester and stupidly put the 6 pin in the 8 pin connection without thinking. A heard a small pop and the psu stopped working. It wasn't connected to anything at the time, I'd taken it out of the pc case.
chances are we can rule out the PSU since it wasn't connected.... but I'm confused on what you actually did to the 6pin and 8pin connectors coming out from the PSU - you plugged them into what to make it 'pop'?
 
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