Question Fried CPU or mobo?

ethanhannay

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There was recently a power outage at my house that damaged my computer. At first I thought that it was only the power supply so I switched it out with another one to test my theory. Unfortunately that was not the issue. I wasn't receiving any kind of display output despite the all of my components receiving power, so I switched out the GPU to see if that did anything. It didn't. I can get my computer to post, but only when it wants to. I've gotten back into windows a couple of times but only when it wants to as well. The power button led lights up only occasionally, but when it does light up it usually posts, but only into safe mode where it tells me if I tweaked anything to revert it back to something stable. CPU and mobo are two components that I don't have spares of or know anyone who does, so I'm not sure if one or the other or maybe even both are toast. Safe mode post
 

InvalidError

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If there were large enough power surges during that outage, there may have been voltage differences between the different external grounds to cause high enough current flows between grounds to damage things. Since the motherboard is the nexus of most external connections, it would be the top contender for most likely casualty after the PSU.

Any power surge from the PSU would have to go through the motherboard's VRM to affect the PSU. Damage there would very likely kill both.
 

ethanhannay

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If there were large enough power surges during that outage, there may have been voltage differences between the different external grounds to cause high enough current flows between grounds to damage things. Since the motherboard is the nexus of most external connections, it would be the top contender for most likely casualty after the PSU.

Any power surge from the PSU would have to go through the motherboard's VRM to affect the PSU. Damage there would very likely kill both.
Thank you for the insight. The irony is I even had the pc plugged into a surge protector so I’m thoroughly upset over the damages.
 

nicholas70

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I wouldn't rely on a surge protector myself, but this isn't to say you shouldn't have one. The best thing you can do is buy a good psu and unplug your system if you are not going to be using it. Even when you do these things you can still get hit with a surge, and when you do you just have to hope that the protector and psu can save your system.
 

ethanhannay

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I wouldn't rely on a surge protector myself, but this isn't to say you shouldn't have one. The best thing you can do is buy a good psu and unplug your system if you are not going to be using it. Even when you do these things you can still get hit with a surge, and when you do you just have to hope that the protector and psu can save your system.
I know surge protectors aren't the be all end all but it would have been really nice if it did it's job literally the only time we've lost power since I built my system. To add to the irony it's a Philips surge protector, which is the company I work for. Go figure.
 

JoshMcD

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I know surge protectors aren't the be all end all but it would have been really nice if it did it's job literally the only time we've lost power since I built my system. To add to the irony it's a Philips surge protector, which is the company I work for. Go figure.

Doesn't the surge protector come with a equipment warranty?
In the UK, Masterplug sockets come with a guarantee of 3 years warranty and up to £1000 equipment protection if a surge does damage components that is connected to the socket.
 

nicholas70

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I would try turning to the power company before attempting to make a claim on the surge protectors warranty. Some power companies will compensate you if equipment failures cause a surge that damages your stuff. If that doesn't work then I'd consider the surge protector or maybe even my home owners policy if the cost of the damage was high. I had a surge hit my system in February when a transformer exploded and now I'm having to replace parts that have started failing. Was the surge the cause? Who knows for sure, but one thing is for sure and that is excess current and voltage kill and degrade electronics faster then anything else.
 
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InvalidError

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A lot of surge protectors aren't worth the paper they're written on tho. Doubtless some beard wagging about that one.
Even the best surge protectors are useless when used incorrectly. If the computer is plugged into a surge protector but is also connected to other stuff that isn't connected to the SAME surge protector, then surges can still travel between protected and unprotected equipment or equipment on different circuits.
 
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bit_user

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Even the best surge protectors are useless when used incorrectly. If the computer is plugged into a surge protector but is also connected to other stuff that isn't connected to the SAME surge protector, then surges can still travel between protected and unprotected equipment or equipment on different circuits.
Don't forget about your Ethernet jack!

You can find UPS models with integrated Ethernet protection, but also standalone Ethernet surge protector modules. I have no idea how good they are (I assume MOV-based, like inexpensive surge-protectors), but they're probably better than nothing.

I would strongly advise using a decent UPS that includes protection from over/under-voltage conditions.
 

InvalidError

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You can find UPS models with integrated Ethernet protection, but also standalone Ethernet surge protector modules. I have no idea how good they are (I assume MOV-based, like inexpensive surge-protectors), but they're probably better than nothing.
MOVs have too much parasitic capacitance to shunt surges on Ethernet ports. Ethernet protectors I have seen use a bridge rectifier to collect positive/negative transients and a DIAC to shunt transients to ground. Some have extra diodes in series to reduce parasitic capacitance between the common positive and negative rails to ground. Nothing special about the diodes either, plain old 1N4007 or similar. Since Ethernet wiring is typically #24 or #26, wiring resistance should limit current to something the diodes can survive unless we're talking lightning strike directly to/through LAN-connected equipment.
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ethanhannay

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Doesn't the surge protector come with a equipment warranty?
In the UK, Masterplug sockets come with a guarantee of 3 years warranty and up to £1000 equipment protection if a surge does damage components that is connected to the socket.
I’ll actually be looking into that. I read on Philips’ website that they have a limited warranty for equipment plugged into the surge protector. Thank you for the heads up
 

InvalidError

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I’ll actually be looking into that. I read on Philips’ website that they have a limited warranty for equipment plugged into the surge protector. Thank you for the heads up
Worth a try, though I'm expecting them to request a detailed description of how everything connected to your PC was hooked up together and if there was an unprotected vector, the claim may be denied.
 

bit_user

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Ethernet protectors I have seen use a bridge rectifier to collect positive/negative transients and a DIAC to shunt transients to ground. Some have extra diodes in series to reduce parasitic capacitance between the common positive and negative rails to ground.
Thanks for the info.

This is a good reminder for me, since my latest router upgrade has a gigabit uplink/WAN port. I first tried running it through my UPS, as before, but found the uplink speed negotiated down to 100 Mbps. So, I actually need to buy a standalone gigabit-capable Ethernet surge protector. If you have any recommendations (i.e. those with the extra diodes), please let us know.
 

bit_user

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Thanks for the info. Here's what I've found.

If they are advertised as 1GBase-T capable, they most likely have those - that was the case for the APC and CyberPower units I remember looking at.
This reviewer claims 1N4007 diodes are not appropriate for Transient Voltage Suppression.



The APC Ethernet surge suppressor has at least 9 of 163 reviews claiming the device failed to protect their equipment. That said, I can understand there are practical limitations of any inexpensive device.



This device claims to use Gas discharge tubes (GDTs). Out of 71 reviews, no complaints of protection failures:


I wonder if some of the complaints about speed issues are really due to bad or marginal cables that people are using with it. Anyway, I think I'll give it a shot.
 

InvalidError

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This reviewer claims 1N4007 diodes are not appropriate for Transient Voltage Suppression.
I'd wager that many of those "GDT" Ethernet surge suppressors have a diode circuit similar to what I put together earlier and simply replace the diac with a GDT. This is kind of necessary since you need your wires to remain within a couple of volts from each other: having eight wires at a few kV and let a per-wire GDT bring ONE of them down to 40-60V before the others when the first GDT trips could be problematic. The diodes keep them all within 1.5V or so from each other so there is no arcing between wires or back-EMF spike in the other wires when the first GDT goes off.
 

ethanhannay

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Short update: I got a spare cpu in today to test the fried cpu theory and I’m posting into safe mode still. I can only get into windows when i set the ram speed to auto rather than overclocking it to 3200 MHz like I normally do. Could bad ram actually be the issue?
 

ethanhannay

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Worth a try, though I'm expecting them to request a detailed description of how everything connected to your PC was hooked up together and if there was an unprotected vector, the claim may be denied.
Everything was connected properly to the surge protector. Everything connected to my pc was also connected to the surge protector (so really only the monitors)
 

InvalidError

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Short update: I got a spare cpu in today to test the fried cpu theory and I’m posting into safe mode still. I can only get into windows when i set the ram speed to auto rather than overclocking it to 3200 MHz like I normally do.
If the computer still works normally with everrything set to stock clocks, then it is going to be extremely difficult to file a successful claim for any sort of damage as the system is still functional under the conditions it is guaranteed to work at.

Since any sort of AC/PSU power anomaly has to go through the motherboard's VRMs before reaching the CPU and RAM, the motherboard is still more likely to get damaged before the CPU and RAM are. If you haven't run memtest86 or equivalent on your PC before, you may want to try that too, maybe you'll discover that one of your DIMMs has a bad bit in which case your boot issues may be purely coincidental with something changing where that bad bit landed in the OS.
 
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ethanhannay

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If the computer still works normally with everrything set to stock clocks, then it is going to be extremely difficult to file a successful claim for any sort of damage as the system is still functional under the conditions it is guaranteed to work at.

Since any sort of AC/PSU power anomaly has to go through the motherboard's VRMs before reaching the CPU and RAM, the motherboard is still more likely to get damaged before the CPU and RAM are. If you haven't run memtest86 or equivalent on your PC before, you may want to try that too, maybe you'll discover that one of your DIMMs has a bad bit in which case your boot issues may be purely coincidental with something changing where that bad bit landed in the OS.
Never heard of memtest before but I’m about to run a test. Thank you for the suggestion
 

bit_user

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Never heard of memtest before but I’m about to run a test. Thank you for the suggestion
If it completes a full run, that should be good enough for typical usage. However, I loop it overnight, whenever I change RAM, motherboards, CPUs, or PSUs, just to be sure. On one or two occasions, it has flagged failures on subsequent passes, after a clean first run.

On one occasion, I found repeatable errors on brand new RAM (running at stock speeds), which I returned under warranty and the replacement passed. I would recommend that to anyone values stability from their system.

Because hardware degrades over time, it's also not a bad idea to run memtest after any crash. Although, I always use a UPS, which pretty much eliminates power fluctuations as a source of system instability, meaning my crashes are always a result of a software or hardware malfunction.
 

ethanhannay

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If it completes a full run, that should be good enough for typical usage. However, I loop it overnight, whenever I change RAM, motherboards, CPUs, or PSUs, just to be sure. On one or two occasions, it has flagged failures on subsequent passes, after a clean first run.

On one occasion, I found repeatable errors on brand new RAM (running at stock speeds), which I returned under warranty and the replacement passed. I would recommend that to anyone values stability from their system.

Because hardware degrades over time, it's also not a bad idea to run memtest after any crash. Although, I always use a UPS, which pretty much eliminates power fluctuations as a source of system instability, meaning my crashes are always a result of a software or hardware malfunction.
The memory test came back clean. It let me reapply the 3200 mhz setting and actually boot without posting into safe mode and the system has worked fine since I installed a new cpu. Thank you everyone for the help and suggestions.