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Electronics => Repair => Topic started by: rdagger on June 30, 2018, 12:43:58 am

Title: Cursed CPU
Post by: rdagger on June 30, 2018, 12:43:58 am
Several years ago I built a PC with an i7 CPU.  After a couple months the power supply died.  I disabled the overclocking and replaced the PS.  A couple of months later the new PS died.  This was suspicious so I swapped out the graphics card for a lower power version and upgraded to a 1000W PS.  This power supply also had a short lifespan. 

I took the computer to my office and forgot about it for a few years.  Recently I pulled it from storage and swapped out the motherboard for a different brand and put in a 4th PS.  After 1 day the PS died (apparently a blown cap).  I’m running it at a different location and the only parts in common with original computer are the CPU, memory and the case.

I’m going to try replacing the caps in the picture.  Could a CPU cause this type of failure?
Title: Re: Cursed CPU
Post by: Mr. Scram on June 30, 2018, 01:05:01 am
It seems most likely that the quality of the PSUs used isn't what it should be. What are you using?
Title: Re: Cursed CPU
Post by: rdagger on June 30, 2018, 01:29:36 am
It seems most likely that the quality of the PSUs used isn't what it should be. What are you using?
OCZ 550W, Rosewill 650W, Corsair 750W, Kingwin 1000W.
Title: Re: Cursed CPU
Post by: TiN on June 30, 2018, 06:32:27 am
Except maybe corsair , all those PSU sound junk to me.

CPU cannot make PSU fail like that, but bad VRM on board of MB can. Over clocking also may cause excess stress to PSU.
Title: Re: Cursed CPU
Post by: Towger on June 30, 2018, 06:53:34 am
Same Kettle lead?
Title: Re: Cursed CPU
Post by: Rerouter on June 30, 2018, 09:40:53 am
That Silver / blue cap, I've been seeing them over and over for the past month, they love failing with reduced capacity with high ESR, then detonate.
Title: Re: Cursed CPU
Post by: rdagger on June 30, 2018, 02:34:20 pm
Same Kettle lead?
Different power cords at home and office.
Title: Re: Cursed CPU
Post by: rdagger on June 30, 2018, 02:36:20 pm
Except maybe corsair , all those PSU sound junk to me.

CPU cannot make PSU fail like that, but bad VRM on board of MB can. Over clocking also may cause excess stress to PSU.
I thought it was the MB too, that's why I replaced the original EVGA MB with a Dell MB.  I guess that one could be bad too.
Title: Re: Cursed CPU
Post by: shakalnokturn on June 30, 2018, 06:08:25 pm
I'd definitely bet on crappy PSU's, all the same make sure airflow is sufficient (is case fan working against PSU fan?)
With a DC clamp meter and decent DMM you could check current is in the PSU's rating on each rail and ripple is not something ridiculous when reaching the mainboard connector.
Title: Re: Cursed CPU
Post by: bob225 on June 30, 2018, 07:10:20 pm
sounds like its either something under the motherboard (a post, or metal swarf)

or

(the most likely) Its a drive starting to fail, HDD's can suffer from heat issues and motor issues what can make the HDD pull excessive current on the 12 and 5v rails

is it a Seagate or a WD Green ?
Title: Re: Cursed CPU
Post by: james_s on June 30, 2018, 08:41:00 pm
It should be almost impossible for an external fault to kill a well designed power supply. I'd say buy a good quality PSU from a reputable source and give that a go.
Title: Re: Cursed CPU
Post by: wraper on June 30, 2018, 08:44:21 pm
sounds like its either something under the motherboard (a post, or metal swarf)

or

(the most likely) Its a drive starting to fail, HDD's can suffer from heat issues and motor issues what can make the HDD pull excessive current on the 12 and 5v rails

is it a Seagate or a WD Green ?
HDD cannot consume high current and keep working. Not to say, none of external faults will kill half decent ATX PSU.
Title: Re: Cursed CPU
Post by: Bashstreet on June 30, 2018, 09:36:47 pm
This really should not happen. Psu's especially cheap ones can break and some corsair models also are noways barely adequate using cheap caps.
Still 4 psu's... hmm

As you have changed the motherboard and i would say cpu is very unlikely to break psu's (not impossible i suppose but..)
Check if you know how safely your wall voltages (use safe meter and do not do it if you unsure what you doing)

It could be that some other component is causing the trouble maybe a hard drive cd player etc (very unlikely...)

Could you send pictures of your system and we can have lil look and try figure what might be going on also take good pictures of the psu maybe we can figure what rail failed.
Title: Re: Cursed CPU
Post by: rdagger on June 30, 2018, 11:13:16 pm
I'd definitely bet on crappy PSU's, all the same make sure airflow is sufficient (is case fan working against PSU fan?)
With a DC clamp meter and decent DMM you could check current is in the PSU's rating on each rail and ripple is not something ridiculous when reaching the mainboard connector.
The last power supply failed with the case side open so I don't think their was an air flow issue.  I have a computer power supply tester that I can use to test the rails on Monday.

Quote
sounds like its either something under the motherboard (a post, or metal swarf)
or
(the most likely) Its a drive starting to fail, HDD's can suffer from heat issues and motor issues what can make the HDD pull excessive current on the 12 and 5v rails
is it a Seagate or a WD Green ?
It could be the Dell MB mounting because it's a non-standard size and I did bodge it in.  I'm running a single SSD hard drive.

Quote
Check if you know how safely your wall voltages (use safe meter and do not do it if you unsure what you doing)
It could be that some other component is causing the trouble maybe a hard drive cd player etc (very unlikely...)
Could you send pictures of your system and we can have lil look and try figure what might be going on also take good pictures of the psu maybe we can figure what rail failed.
The electrical at my home isn't great but it was connected to an APC battery.  The electrical at my office is top notch.   I'll post some pics.
Title: Re: Cursed CPU
Post by: Bashstreet on July 01, 2018, 12:23:32 am
If you run only 1 ssd drive i cannot imagine this causing problems.

I am starting to think that it might actually be the processor this would be very unlikely and i do not think i personally ever witnessed processor causing psu failures.
Defiantly check the case mounting that there is no shorts.

Sorry for your troubles if we can try track what rail has caused the psu to go bad we could potentially narrow the issue further.

Title: Re: Cursed CPU
Post by: wraper on July 01, 2018, 12:28:04 am
If that was CPU, motherboard would fail first
Title: Re: Cursed CPU
Post by: coppice on July 01, 2018, 06:34:44 am
Is this one of those Dell motherboards with the standard ATX power socket, but a non-standard use of its pins?
Title: Re: Cursed CPU
Post by: bob225 on July 01, 2018, 04:06:42 pm
sounds like its either something under the motherboard (a post, or metal swarf)

or

(the most likely) Its a drive starting to fail, HDD's can suffer from heat issues and motor issues what can make the HDD pull excessive current on the 12 and 5v rails

is it a Seagate or a WD Green ?
HDD cannot consume high current and keep working. Not to say, none of external faults will kill half decent ATX PSU.

cant it ? well I have replaced melted molex and sata connectors over the years with work drives
Title: Re: Cursed CPU
Post by: wraper on July 01, 2018, 04:17:39 pm
sounds like its either something under the motherboard (a post, or metal swarf)

or

(the most likely) Its a drive starting to fail, HDD's can suffer from heat issues and motor issues what can make the HDD pull excessive current on the 12 and 5v rails

is it a Seagate or a WD Green ?
HDD cannot consume high current and keep working. Not to say, none of external faults will kill half decent ATX PSU.

cant it ? well I have replaced melted molex and sata connectors over the years with work drives
It may happen because of bad contact, not because of higher than normal power consumption. Do you really think that HDD could consume something in order of 100W+ to have any effect on PSU and not burn in flames?
Title: Re: Cursed CPU
Post by: bob225 on July 01, 2018, 04:23:00 pm
Did you use the same mounting screws for each psu ? depending what dell board it is it may have a custom psu and the atx plug is but pinned out differently

usually it wont boot or the board will let out the blue smoke
Title: Re: Cursed CPU
Post by: andy2000 on July 02, 2018, 02:44:54 pm
I vote for poor quality, or defective power supplies.  Even if there was something seriously wrong with the CPU or motherboard, any half decent power supply would simply shut down without damage. 
Title: Re: Cursed CPU
Post by: mikerj on July 02, 2018, 04:59:09 pm
I vote for poor quality, or defective power supplies.  Even if there was something seriously wrong with the CPU or motherboard, any half decent power supply would simply shut down without damage.

Four power supplies across four separate brands seems (literally) unbelievably unlucky.
Title: Re: Cursed CPU
Post by: james_s on July 02, 2018, 06:14:47 pm
Unless they're all garbage, could be counterfeit ebay junk that is guaranteed to fail, we don't really know.
Title: Re: Cursed CPU
Post by: rsjsouza on July 02, 2018, 07:19:28 pm
Despite you have replaced the motherboard, as others have said I can imagine a bad VRM taking the system down.

In a very distant past my main computer was a Dual Pentium II 300MHz and I had an issue that almost took my power supply with it: one of the MOSFETs of the Vcore voltage regulator failed short and was putting almost 3V into the CPU0, which in consequence started consuming an immense amount of power. The computer was still operating normally and I only noticed the Ampère smell coming from inside the computer.

At the time I was using a ~400W (untested) power supply and a Supermicro motherboard. They repaired the board for free - a feat given it was completely out of warranty and I had to ship it from Brazil to US.

Fast forward many years, I had a crap power supply and its mildly "out of mechanical tolerance" contacts inside the main connector almost ruined the motherboard receptacle - as wraper said, the minor sparks caused by the poor contacts started to melt the plastic due to the increased temperature. In this case, the symptoms were easier to notice: the computer randomly failed. Replacing the power supply with a high quality Corsair with detachable cables solved the problem. The POS is still in my junk storage, but it has a big red X on it.
Title: Re: Cursed CPU
Post by: Bashstreet on July 02, 2018, 07:44:10 pm
I vote for poor quality, or defective power supplies.  Even if there was something seriously wrong with the CPU or motherboard, any half decent power supply would simply shut down without damage.

Four power supplies across four separate brands seems (literally) unbelievably unlucky.

Yes i would think it very unlikely.

It would be quite informative to see what actually broke in the PSU's so lets hope the OP can give us some further pictures so we can have proper look.
Title: Re: Cursed CPU
Post by: james_s on July 02, 2018, 09:48:53 pm
Unlikely yes, but I find the idea of a motherboard or CPU killing power supplies to be at least equally unlikely. I too am curious to know what the root cause turns out to be.
Title: Re: Cursed CPU
Post by: rdagger on July 02, 2018, 10:40:04 pm
Despite the blown cap shown in my first post, the power supply tester shows that the PS is OK (for what it's worth).  During testing, I hooked the PS up to a 1 amp server fan.  The tester does not put a load on the PS.  Unfortunately I stripped the CPU cooler mount when I removed the PS so I'll have to wait until I can tap a new mount.

btw:  The blown cap is under the bundle of wires at the bottom right of the photo.
Title: Re: Cursed CPU
Post by: shakalnokturn on July 02, 2018, 10:55:15 pm
What more does a PSU tester do than the voltage monitor in the BIOS?
Title: Re: Cursed CPU
Post by: rdagger on July 02, 2018, 11:12:41 pm
What more does a PSU tester do than the voltage monitor in the BIOS?
Nothing, but the computer won't boot to BIOS.  It definitely won't tell definitively if the PS is good.

I'm leaning toward a bad motherboard.  I'm going to put the PS back together and throw it in another computer.  I think it might work despite the bad cap.
Title: Re: Cursed CPU
Post by: rdagger on July 02, 2018, 11:47:27 pm
Am I wrong about the failed cap?  Is it a Chemi-con aluminum polymer 470uF 16V cap?  Could the brown discharge on the side be something else?
Title: Re: Cursed CPU
Post by: james_s on July 03, 2018, 12:46:08 am
I suppose it could be some kind of glue, I can't tell from the picture where it came from since it's on multiple parts.
Title: Re: Cursed CPU
Post by: andy2000 on July 03, 2018, 01:28:27 am
It looks like glue to me, but clean it off and see what's underneath to be sure.  One thing is certain, no overload could cause a cap to blow its top.
Title: Re: Cursed CPU
Post by: rdagger on July 03, 2018, 02:34:54 am
It looks like glue to me, but clean it off and see what's underneath to be sure.  One thing is certain, no overload could cause a cap to blow its top.
I think you're right. I misdiagnosed the bad cap (rookie mistake).  It looks like yellow glue that turned brown from heat.  There's probably nothing wrong with the PS.  I guess it's the MB.
Title: Re: Cursed CPU
Post by: bob225 on July 03, 2018, 10:25:41 am
pull the board out of the case and bench test it, reset the bios and use the onboard graphics