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Question Dead system: help me figure out if it is the motherboard, CPU, or power supply

Lil'John

Senior member
Dec 28, 2013
228
4
81
Symptoms: CPU fan cycles on/off when I try to power up the system. No VGA video transmitted. No speaker beeps.

Parts:
MB Gigabyte GA-H110-D3A rev 1.0
CPU: Intel 6700k using Intel cooler
Memeory: G.Skill RipJaws F4-3200C16D-32GVK (two sticks for 32GB?)
Powersupply: EVGA 500W
Case: open air test bench (known working, unknown brand)

Short: Is it a bad motherboard, CPU, or power supply?

Long: All the parts but the MB and power supply came from another system where I fried the motherboard(ASRock Fatality) while it was on the open air test bench. Basically, something metal fell on MB. The old system was put in service around late 2015.

I got the Gigabyte MB fairly cheap and if it is working, will work for what I intend. I know it is a mining MB and wastes the potential of the 6700k so let us not go down that rabbit hole.
 

DrMrLordX

Lifer
Apr 27, 2000
17,842
6,816
136
In summary: the old board fried, so you swapped in a new board and now it won't POST.

My gut tells me CPU. If you had a short on the old motherboard that killed the system, odds are good it killed the board and the CPU at the same time from a voltage spike. I had that problem while mishandling CLU during teardown on my old 1800x/x370 Taichi system. Different platforms, granted, but still. In my case, not only was my x370 Taichi dead, but my 1800x was also dead AND was capable of taking other motherboards with it! It killed another board before being forced into retirement. You can try the usual steps: swap out sticks of RAM into singles or replace them entirely, swap out PSU, etc. to see if you can get the system to at least POST. But my gut is telling me that the 6700k is dead. I doubt your 6700k will kill other boards like my 1800x was doing but you never know.

Alternatively you can put the 6700k into a known-working system that can support it and test it there.
 
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Lil'John

Senior member
Dec 28, 2013
228
4
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@DrMrLordX Good summary.

I just wrapped up checking the voltage on the PSU and all the lines were consistent when it was attempting to power up(CPU fan spinning up) and zero when it was off(CPU fan spinning down): yellow 12V, red 5V, orange 3.5V, gray 5V, and purple 5V. Granted, this doesn't guarantee that the PSU is putting out the required amperage.

It also shows that the PSU is getting cycled.

I have some new memory on the way that was selected base upon the board "recommended memory" section.
 

maluckey1

Senior member
Mar 15, 2018
263
103
86
Voltage at the line does not equal good PSU. Even a bad PSU can have voltage to all lines. In your situation, and the history of the PSU, I would test the PSU before anything.

Thermaltake DR Power is cheap and effective at finding bad PSU's. I have one, and it worked great. In my case, the only symptom in an overclocked daily gaming rig, was that sometimes it would cycle into BIOS after a shutdown, and the overall overclock wasn't reaching what I felt the setup should reach.

Dr.Power II (thermaltake.com)

M
 

Lil'John

Senior member
Dec 28, 2013
228
4
81
Voltage at the line does not equal good PSU. Even a bad PSU can have voltage to all lines. In your situation, and the history of the PSU, I would test the PSU before anything.

Thermaltake DR Power is cheap and effective at finding bad PSU's. I have one, and it worked great. In my case, the only symptom in an overclocked daily gaming rig, was that sometimes it would cycle into BIOS after a shutdown, and the overall overclock wasn't reaching what I felt the setup should reach.

Dr.Power II (thermaltake.com)

M
The PSU I have plugged in has no history... it is a virgin PSU I bought for my mini case and found out that it was too big.

The PSU that was attached to the old fried motherboard is not currently being used. I might have used it but it was short a plug for the MB(four pin plug instead of eight pin)
 

Soulkeeper

Diamond Member
Nov 23, 2001
6,648
105
106
My gut is telling me to suspect your PSU. Really all you can do is swap parts out and see what works.
You could use a flashlight and look inside the psu, if it has the openair holes to allow this. Look for swollen capacitors.

Something like this:


Modern motherboards and PSUs have overcurrent/overvoltage protection features. Which could account for the power on then power off you're seeing. If the voltage is not stable.
 

Soulkeeper

Diamond Member
Nov 23, 2001
6,648
105
106
Also check all connectors. Look for any kinda of melting or signs of damage from a short (from your previous problems). I've seen ATX pins get damaged from such things.
 
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Lil'John

Senior member
Dec 28, 2013
228
4
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Ahhh...my reading comp skill = 0.
No worries. Lots of text surrounding that detail;)

My gut is telling me to suspect your PSU. Really all you can do is swap parts out and see what works.
You could use a flashlight and look inside the psu, if it has the openair holes to allow this. Look for swollen capacitors.
<snip pic>
Modern motherboards and PSUs have overcurrent/overvoltage protection features. Which could account for the power on then power off you're seeing. If the voltage is not stable.
PSU is so far out of warranty, I'll just pop it open to take a look

Also check all connectors. Look for any kinda of melting or signs of damage from a short (from your previous problems). I've seen ATX pins get damaged from such things.
The PSU that was involved in the previous motherboard isn't in use. It didn't have an eight pin aux MB power connector :(

I did another test on the new EVGA PSU using a manual power on plug on the 24pin MB plug from the PSU. This is one of the jumper plugs that fully powers the PSU. I spot checked a couple of the power wires and they didn't cycle.

I think this points toward the PSU being in good shape.

I also replaced the memory with a new 4GB that arrived today. It didn't change the cycling behavior noted.

I think this narrows it the new motherboard or old CPU. The MB was sold as working. The old CPU was involved in the old board short-out. On the prowl for a reasonable price Skylake or Kaby Lake of some wort:/
 

Lil'John

Senior member
Dec 28, 2013
228
4
81
I can't 100% confirm whether the MB was fried. But it appears the CPU was dead.

To recap what I did:
Dropped something metallic on MB and system stopped working.
I tried all sorts of BIOS resetting on existing MB
I ordered a replacement MB
New MB didn't start
I tried all sorts of BIOS resetting on new MB and system didn't work
I ordered a new CPU and it all worked

I did not replace the power supply. In hindsight, it might have been cheaper to just order a lower end current system except for replacing 32GB memory.
 

meganin

Member
Jan 19, 2017
111
1
81
I can't 100% confirm whether the MB was fried. But it appears the CPU was dead.

To recap what I did:
Dropped something metallic on MB and system stopped working.
I tried all sorts of BIOS resetting on existing MB
I ordered a replacement MB
New MB didn't start
I tried all sorts of BIOS resetting on new MB and system didn't work
I ordered a new CPU and it all worked

I did not replace the power supply. In hindsight, it might have been cheaper to just order a lower end current system except for replacing 32GB memory.
hey thanks for update , i have a dg41cn with kinda same power cycling problem, did everything like you,even started a thread here (old) ,i gona try with some cpus in my working mobo,to see if old cpus are ok. and swap in around to check if anything works.
 

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