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PC Does Not Power On When 8Pin EPS Plugged In. CPU or RAM Dead?

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November 19, 2012 6:58:18 AM

Update: The CPU was dead, so I received my replacement today :D  I confirmed it was dead by testing it in a working Cougar Point system.


This post will be edited with the latest information, so you shouldn't have to read the whole thread.



SYSTEM SPECS
Mobo: ASUS P8P67 Pro 3.0
CPU: 2600K @4.6GHz, 1.3611VID, 24/7 F@H Stable ~65*C
CPU Heatsink: NH-D14
RAM: MV-3V4G3D/US (Samsung "Magic" RAM), 16GiB, Stock BIOS Settings
PSU: SeaSonic X-850
Main OS HDD: WD Black 1TB
GPU: GTX 570


SUMMARY
I set my memory overclock to 2133MHz, and adjusted the timings and voltages accordingly. Then I booted into Win7PE, and about halfway through the boot my PC shut itself off. I was unable to turn it back on, so I tried to clear the CMOS. The PC would still not boot, except when the 8Pin EPS is unplugged.


BACKGROUND
I test my overclocks in Win7PE with Prime95 Blend 14400GB. On November 17 I decided to stress test the following memory overclock:
- 2133MHz
- 11-11-11-28-2, tWCL 9
- 1.575V
- 1.1VCCIO


INCIDENT
I booted into Win7PE, which runs off a USB 3.0 flash drive, and my PC shut off during the windows loading screen. I didn't notice anything abnormal when it shut off, so I pressed the power button to turn it back on. The PC did not POST.


ACTION TAKEN
Here is what I have done to troubleshoot, but with some obvious steps skipped:
1. Cleared the CMOS twice by following the instructions in my manual, but my PC would still not POST after each attempt.
2. Tried the alternate instructions 3 times (removing the battery), and my PC was unable to POST after each try.
3. Unplugged the 24Pin from my mobo, and stuck a paper clip in the Power On (Green wire) and Ground (Black wire) to start the PSU.
4. Plugged in the PSU and turned it on, but the result was same as the first time I tried turning the PC back on.
5. Measured the voltages on the 24Pin, and got
- 3.25V on Power On (Green wire).
- 5.12V on +5VSB (Purple wire).
- 0.00V on Everything else.
6. Checked the PCI-E and 4Pin peripheral voltage, but there was none.
7. Tried resetting the PSU by following the instructions in the manual, but the PC would still not start.
8. Unplugged everything but the 24Pin from my PSU.
9. Turned on the PSU, and checked the voltages on the 24Pin, and got the following results:
- 5.05V
- 3.38V
- 12.30V
So the power supply works.
10. Plugged in the 8Pin EPS, but the PSU would not turn on.
11. Unplugged the 8Pin EPS, then plugged in everything else.
12. Turned on the PSU, and observed everything turn on.
13. Measured the 8Pin EPS voltage, and the result was 12.30V.


OTHER INFORMATION
When I press the power button, it sounds like its going to turn on for a split second, but then powers down. None of the components actually power on though, so the sound must be coming from the PSU. The PSU is ~1.5 years old, and has been under light (CPU only) load for most of it's life.


QUESTION(S)
What should I do next to troubleshoot?
What component(s) need(s) to be replaced?
a b ) Power supply
a c 89 à CPUs
November 19, 2012 7:23:34 AM

first, remove all your components from the case. Now on an insulated surface, plug in only the motherboard, ram, cpu and connect up the psu. Power on and see what happens. If it works, start adding one other component at a time. It could be something shorting out in the case or a faulty component pulling the psu down or bad connection or something. If it fails in a bare minimum config, see if you can borrow a psu from somewhere to test.
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November 19, 2012 7:50:06 PM

iam2thecrowe said:
first, remove all your components from the case. Now on an insulated surface, plug in only the motherboard, ram, cpu and connect up the psu. Power on and see what happens. If it works, start adding one other component at a time. It could be something shorting out in the case or a faulty component pulling the psu down or bad connection or something. If it fails in a bare minimum config, see if you can borrow a psu from somewhere to test.

Can I leave my PSU in the case when I do the tests? I remember it being a PITA to put in, and that was before the mess of cables.

I don't have a motherboard speaker, so how can I confirm if the mobo, RAM, and CPU combination works? Would plugging in a fan to one of the mobo headers be a sufficient test? Or should I check some voltages?
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Related resources
a b ) Power supply
a c 89 à CPUs
November 19, 2012 7:56:51 PM

well you plug a monitor in of course. and you should definitel have the cpu fan and heatsink on. would be best to remove the psu, its only 4 screws and its out.
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November 19, 2012 8:06:24 PM

iam2thecrowe said:
well you plug a monitor in of course. and you should definitel have the cpu fan and heatsink on. would be best to remove the psu, its only 4 screws and its out.

Spoiler
Because I'm using a P67 mobo, I would need to plug in my GPU for the video output. Would that still be fine for testing?

My CPU fans are 3x0.35A, and are usually powered by my fan controller. So I'll use lower powered (0.123A) fans to check the mobo fan headers.

It's not quite that easy to remove the PSU in my case, but I'll re-think it.


$6 shipping for a $2 mobo speaker at CWC :o  Maybe I should be buying local, or eBay.

Ignore the above.

Here is what I have done today, November 19, to troubleshoot, but with some obvious steps skipped:
1. Tried resetting the PSU by following the instructions in the manual, but the PC would still not start.
2. Unplugged everything but the 24Pin from my PSU.
3. Turned on the PSU by connecting the Power On to Ground, then flipping the switch to "I".
4. Checked the voltages on the 24Pin, and got the following results:
- 5.05V
- 3.38V
- 12.30V
So the power supply works.
5. Plugged in the 8Pin EPS, but the PSU would not turn on.
6. Unplugged the 8Pin EPS, then plugged in everything else.
7. Turned on the PSU, and observed everything turn on.
8. Measured the 8Pin EPS voltage, and the result was 12.30V.

IIRC, the 8Pin EPS powers the CPU and RAM. So either the CPU or RAM died, correct?

Taken from the OP:
What should I do next to troubleshoot?
What component(s) need(s) to be replaced?
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November 20, 2012 3:14:46 AM

Updated the OP with the latest info, and changed the thread title to reflect the current problem.
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!