Question PC won't power on

Vybz

Member
Dec 27, 2007
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Not sure this is the right place for this question.

My PC is alittle dated and is now not even powering on. After running through quite a few troubleshooting steps I narrowed down the issue to the 4x4 pin power cable for the CPU. If I unplug it the system powers on but once plugged in it does not come on. It comes on with everything else plugged in.

I have tried to take out the CPU clean it and reinstall it with new thermal paste, but that has not worked. What else can I try? Is the issue the CPU? here's the build:

CPU: Intel Core i5-8400
Motherboard: ASRock Z87 Extreme3
Ram: Team DDR3 1600 16GB
SSD/HDD: Crucal M500 240GB, WD Blue 1TB
GPU: MSI GAMING GeForce GTX 1060 6GB GDRR5
PSU: Seasonic FOCUS Plus Series SSR-650FX 650W 80+ Gold
Chassis: Corsair Obsidian 550D
OS: Windows
Monitor: dual dell monitors
 

Tech Junky

Senior member
Jan 27, 2022
840
271
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Well, the 4-pin lead is or OC'ing for additional power. The lead might just need to be replaced. If it's not the lead then it could be the jack it plugs into and that would mean a new MOBO but, you won't lose any performance by not using it.
 

WilliamM2

Golden Member
Jun 14, 2012
1,837
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Well, the 4-pin lead is or OC'ing for additional power. The lead might just need to be replaced. If it's not the lead then it could be the jack it plugs into and that would mean a new MOBO but, you won't lose any performance by not using it.
The 4 pin is not for overclocking, it powers the CPU and IS required. In my experience, with the cable unplugged the system will power on, but it won't initialize and boot.

OP wasn't clear on what he meant by "powers on".
 

C1

Platinum Member
Feb 21, 2008
2,273
62
91
A scenario that fits what is happening is that the PSU thinks it is seeing a "short" when the 4-pin connector is plugged in, so, for protection, the PSU does not energize.

In an attempt to test such theory, first check to ensure that your MB doesnt have an EZ_PLUG option. If so, try that, otherwise purchase a suitable molex to 4-pin adapter then try that combination.
 

Vybz

Member
Dec 27, 2007
118
10
81
Well, the 4-pin lead is or OC'ing for additional power. The lead might just need to be replaced. If it's not the lead then it could be the jack it plugs into and that would mean a new MOBO but, you won't lose any performance by not using it.
Its not a 4 pin. its 8 but you use a 4x4 plug. see the plug in the picture and its labeled CPU
Z87.jpg



The 4 pin is not for overclocking, it powers the CPU and IS required. In my experience, with the cable unplugged the system will power on, but it won't initialize and boot.

OP wasn't clear on what he meant by "powers on".
yes it is required and what I mean by power on is that the PC does not turn on at all. so its does not start post becuase it just does not power on unless in plug out that cable. and since its the CPU cable nothing happens.


Might be a different case with older PSU / MOBO / CPU since more recent ATX setups have a 8-pin + 4-pin. CPU only needs the 8-pin to run not the 4-pin since it's just additional power if needed for boost / turbo / OC.

View attachment 61176
see above for the mobo and the plug I mean.


A scenario that fits what is happening is that the PSU thinks it is seeing a "short" when the 4-pin connector is plugged in, so, for protection, the PSU does not energize.

In an attempt to test such theory, first check to ensure that your MB doesnt have an EZ_PLUG option. If so, try that, otherwise purchase a suitable molex to 4-pin adapter then try that combination.
what do you mean where would I plug that molex to 4 pin?
 

C1

Platinum Member
Feb 21, 2008
2,273
62
91
Presumably you are dealing with the 4+4 pin connector (ie, the 8 - pin 12v CPU ATX PSU supply connector) and not, as you stated, some other 4x4 pin connector (ie, 16 pins).

Look at this thread - hopefully should help:

 

Vybz

Member
Dec 27, 2007
118
10
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I'm sure Vybz means 4+4...
Yes that's what I meant. that's why I am so confused here. I tried different cables already because I have more than one. so its not the cable. Am I correct in thinking that only the Mobo and CPU could be the problem?
 

lakedude

Platinum Member
Mar 14, 2009
2,481
213
106
Am I correct in thinking that only the Mobo and CPU could be the problem?
CPUs very rarely go bad. Last bad CPU I can remember was a Cyrix. Maybe an AMD when a heatsink fell off during shipping back before they put thermal sensors in their chips. I mean it could be a bad CPU but that is just so rare.

The PS and MB are the likely suspects. This whole 4+4 plug thing is especially suspicious. Are your PS cables labeled? Don't use the similar looking cable for the video card! Or the +4 from the main 20+4 pin!!

I mean are you 100% sure the cabling is correct?
 
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