Computer Hope
Hardware => Hardware => Topic started by: duckworth on March 30, 2014, 06:29:57 PM
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Hello,
I'm used to diagnosing and replacing hardware.
I'm not sure how to proceed with this problem though.
I plug in the computer and sometimes it will power up and run for days.
If I restart it ... it will restart and continue running.
I can turn the power off and everything is "ok" ...
If I push the power button on the front of the computer it will flip the breakers beside the kitchen most of the time now.
The computer completely shorts out and flips the associated breaker when powered on.
(in the beginning problems with restarting the computer were rare)
There is no visible damage to the motherboard or the cards in the computer I can see without removing it.
I have removed most external connections with power.
The hardware :
Norco RPC-470 Case
Asus m4a89gtd pro/usb3 motherboard
AMD 905e processor (low power)
Kingston Hyperx DDR-1300 2x2GB
4x hauppauge WinTV-HVR-2250
3x hauppauge HD-PVR2 Gaming
connectland USB 3 powered 4-port hub
60GB Ocz SSD
4 x 250 GB WD Sata drives
2 x USB-UIRT
APC Back-UPS ES 750VA
The previous power supplies
500W Nmedia
650W antec power trio
Current power supply
750W fractal design Integra
I replaced the power supplies twice thinking they were the problem, as most times the computer pulls less than 150 Watts at peak via the APC Backups software. (and a Kill-a-watt)
Now on my third power supply in 4 years I'm having this problem more often than not.
I'm curious where to start looking on/in the system to find the short?
If something would just completely stop working I would replace it or if it were visibly damaged ...
Tomorrow morning I will start removing and inspecting all parts and possibly moving it all to a new case.
I've never had to try finding a nebulous short in a computer system that sometimes works and I'm not sure about the safest way to proceed
It's a windows 7 install so just swapping out the motherboard with onboard graphics might be troublesome.
Thanks for your time and any help,
Bobby
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You may want to call an electrician.
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You may want to call an electrician.
Actually, that is the best answer.
A bad cord can do that. Or a defective wall socket.
Using a bigger power supply will not repair the cord ...
- or a wall socket. Trust me on this. :D
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swapped computer on that power cord with one in the living room earlier
that computer powers up on that circuit with that APC UPS and that powercord without trouble (all indicator lights showing circuit as grounded)
so it doesn't look like the wiring in the walls, that socket, that UPS or that powercord
The short appears to be inside the computer and appears to be intermittent causing the confusion
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Some details about your computer case and the wiring in your house.
Where do you live?
How old is the house or living unit?
Here in North America the socket must be wired exactly as code specifies. But if the wires have been swapped or if their there is any irregular connection in the house wiring, shorts can happen and are not predictable without actual measurements. That is why electricians use some special devices to prove how circuits are wired. A UPS is not an diagnostic tool per se.
A normal power supply of a ATX design can not thorough breaker on a moderate overload. The house breaker in the USA trips on current flow above 15 amps for more than a fraction of a second.Consulting a chart shows that a 15 amp breaker will hold 14 amps. An overload at 20 amps breaks in about 150 milliseconds. At 16 amps it is not specified.
On a 120 volt system, standard in USA, 12 amps at 120 volts is 1440 watts. Your 700 watt supply should disconnect or shut down at 900 watts or less. And it does that much faster than the mechanical brander can respond. So the idea of computer motherboard, drives or anything feeding from the PSU would trip a standard breaker is absurd. The 700 watt PSU can not take over t 10 amps by legal codes that apply to it. We shall not assume you had three PSUs that were in violation of electrical codes. Bad house wiring is much more often the flaw.
The only rational explanation is the wall socket has not been wired properly.
Now did you say you live in another country? Sorry, I missed that.
Maybe in in other courtesies even more power is required to through breaker. If so, the idea of it being the PSU or computer is just out of the question.
EDIT: Sorry, I bad quoted the codes. Here in USA a breaker is not required to have a quickie response time. It only has to be able to prevent a fire or damage to wires. Theatmeans moderate overload will go on for minutes .
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The motherboard could be shorted to the case, but in such a way that contact is only made intermittently.
The UPS- could be the problem as well, it could be failing.
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Hi
A computer short would not blow the circuit breaker. At most it would cause the computer power supply to shut down until the short is cleared.
Is it a standard circuit breaker or an RCD ?
RCD's will trip on a very low residual current as you could get with say the APC UPS and a printer plugged into a different socket but on the same RCD connected to the computer via USB. Especially if you used insulating washers on the motherboard mounts and the motherboard isn't grounded ?
If it is a standard 15 or 20 amp circuit breaker that was tripping, you would see and smell where the short is as that is a lot of current and therefore watts which have to go somewhere :)
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It could actually be another item plugged in elsewhere. eg. it could be on the same circuit as other devices that only turn on occasionally on a timer, such as electric heaters, a refrigerator, freezer, etc. It would be intermittent because it might only be when the PC and a number of other components are on that the breaker goes.
I recall a friends house where turning on the coffee maker and electric kettle while the refrigerator was running would trip the breaker.
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BC_Programmer,
You got the best answer. That has to be the scenario.
If the PSU is working normally, any short circuit in a computer can not trip a thermal breaker by itself.
As BC said, a fridge could come on line at the same time the op turns on his computer. The breaker will trip if:
A.) The broker is failing or is the wrong kind.
OR
B. The fridge is consuming more that its rated current.
The OP needs to come back and tell about his house wiring. Where does he live? How old is the house? has there ever been electrical problems? The fact tghat he has an APC** would suggest there has been a history if electrical problems.
Did he mean UPS?
http://en.wikipedia.org/wiki/Uninterruptible_power_supply
is an electrical apparatus that provides emergency power to a load when the input power source, typically mains power, fails. A UPS differs from an auxiliary or emergency power system
** APC = APC Back-UPS ES 750VA
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I live in Vancouver, BC, Canada
The building is from the fifties, but the suite I'm in appears to have been added on the roof after completion.
(suites on lower floors have fuses)
I can't tell what breaker type other than it has on / off / flipped.
This computer is in a NorcoTek RPC-470 case with metal motherboard tray and metal standoffs with metal screws smaller than the white circles denoting the mount point on the motherboard.
My main computer is in the same case, (I have an extra from in between builds) and my NAS is in a similar case by the same manufacturer.
The cases didn't come with insulating washers, neither did my two Antec 900 cases, my Thermaltake case or my Cooler Master full tower case that I built my first NAS in.
I do have a screw bag from 15 years ago from one of the many computer builds I have done with some insulating washers in it I think ... if I can find them.
I'll see if I can buy a package of insulating washers bulk.
I haven't seen those paper insulating washers come with a computer case or a motherboard in many many years, I think that would have been a Pentium 133 build when it cost $1600 for the complete system.
I started buying bigger power supplies after I started building NAS's and the hard drives also started requiring more power on spin up ...
(so if a system went down I could swap a Power Supply from a working system to the broken one if needed, until I could go to the computer store)
(I wasn't trying to flip the breaker faster, just make my setups more universal)
On that wall socket with the original APC Backups ES 750 and an exchanged power cord ...
My HTPC flips the breaker
(150 max draw on boot via kill-a-watt when built)(runs between 100W and 150W as reported by the UPS)
I exchanged my main computer with my HTPC ... main computer boots and works ...
I exchanged my NAS with my main computer ... NAS boots and works ... (same motherboard as HTPC, with phenom 6 core, 2x4GB RAM and 16 hard drives) (150W spun down to 300W on boot via Kill-a-watt)(runs between 150W and 230W as reported by the UPS)
I exchanged the APC Backups ES 750 and hooked it up to my NAS on the same wall socket and it boots and works with the new power cord
I exchanged my main computer with the NAS and hooked it up to the new power cord and the exchanged UPS and it booted up and worked.
I hooked up my HTPC to the exchanged UPS and the new power cord and it flipped the breaker.
I checked the wall socket ... looks in good condition with ground wire ... can't tell how it's wired at the other end though and yes I understand without proper test equipment I'm guessing.
A computer at a time I have cycled seven computers through this wall socket in the last 10 years, so I'm really hoping it's not the wall socket and wiring.
It may be absurd, but the breaker is flipping ... and it has me really confused
It may be the overload from the HTPC causing the UPS to draw current on top of the short circuit in the HTPC ?
I have removed all drives and all cards from the HTPC
I can turn on the HTPC about 50% of the time and it will power up ... if I reset it ... it will reboot ... as many times as I hit the reset button
If I turn it off and then turn it back on in under a minute it shorts.
I am about to remove the motherboard to check for loose metal ... I don't know if I should move the motherboard to a new case and try that ...
Both UPS's passed their last self tests within the last month if that means anything ?
The wiring includes two bedrooms on one circuit with no heavy appliances ... My roommate has a laptop and a LED LCD with a cablebox in his room.
I have two APC Back-UPS ES 750 Uninterruptible Power Supplies one for my HTPC to shutdown gracefully and one for my NAS to shutdown gracefully as a parity rebuild takes 16 hours.
I got them because it was suggested for the NAS and I thought it would be good for the HTPC also.
and sorry for the rambling, working nights
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duckworth,
Thanks for coming back with details.
I believe the codes in your are are similar to what we have in the USA.
Short answer: You need to replace the breaker in that electrical circuit.
A 15 amp thermal breaker should hold for over two minutes at 30 amp surge.
This problem is not a power supply thin g.
The problem is not the washers you have on the motherboard.
You have an intermittent problem.
It is normal for some motherboards to draw a lot of current at stat -up. Nevertheless, the PSU has to control the surge current. That is its job. Any normal PSU has a rating of 8 to 12 amps max surge current for one second or less. That is not enough to trip a thermal breaker that meets code.
The only effective way to test a thermal breaker is to replace it.
General reference for North America.
http://www.moeller.net/binary/ver_techpapers/ver939en.pdf
3
Differences between relevant electrical
standards and market conventions in
both North America (primarily the US
and Canada) and the IEC world play
a key role in shaping the design and
determining the proper application of
products such as
NZM molded case circuit breakers and
NS molded case switches,
N, PN switch-disconnectors,
and combination motor starters in
those markets.
North American electrical product
standards differentiate in signifi-
cant respect between equipment
deemed suitable for energy distribu-
tion (such as UL 489) [1]
versus those components normally grouped
under industrial control (per UL 508/
UL60947) [2]. This type of differentia-
tion is not known in the IEC world. ...
Sorry if that is confusing. But in short, circuit breakers shall allow high surge currents below the fire danger threshold. Which is much hihger that the 15 amp rating of the breaker.
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I know when I plug in the unused molex connector on my XFX 850 W power supply (XPS-850W-BES) it acts as you described no breaker flips ...
it pops the capacitors on that backplane in the NAS and keeps 'cycling' on and off.
It tries to power up and then shuts off, powers up and shuts off, powers up and shuts off ... the BIOS self test never getting a chance to start.
XFX gets their power supplies made by silverstone or some other big name, high quality power supply manufacturer,
but that one connector has the wiring reversed in comparison to the other molex connectors.
It cost $55 plus shipping before I started looking at a connectors wiring before plugging them in.
I guess with that power supply I could just move the pins to the correct places ...
currently I have it wrapped in electricians tape.
Removed everything from the case checked that there was no damage to the motherboard or it's capacitors.
Nothing loose found in the case.
In the past I would notice trouble starting up the current system in question ...
Sometimes I would hit the button and the computer would start ...
Sometimes when I would hit the button and nothing would happen.
When this was happening before the breaker started flipping I thought it was just a finicky switch.
No breaker was flipping at that time ...
The breaker has only become a problem with this computer ... (4 years old)
With this power supply (November 19, 2013)
With an APC Back-Ups ES 750VA (that's two years old)
and only within the last week.
The UPS can only deliver 450W / 750VA so if the shorted computer was spiking higher than that and the UPS wasn't stopping a spiking power draw from the computer ?
or just replace the breaker
or insulating washers ...
Thanks for everyone's time and help,
Bobby
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Get some brass MBoard standoffs and install them properly...although i still don't think it's the issue.
If it persists have the UPS battery tested...
If it still persists call an electrician.
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I'm using the brass motherboard standoffs that came with the case ...
with the "small" headed metal screws that came with the case
and they are installed correctly
UPS batteries are passing self tests ...
is there an inexpensive battery tester I could check it with?
other power supplies I have react as they should when shorted
this one does not appear to (Fractal Design Integra)
will replace with 750 Watt XFX Black Edition power supply and different motherboard (same model) tomorrow
I'm sorry I keep prattling on about this ...
it's just only that one system that has the problem on that circuit ...
I've brought up both other computers together on that circuit without trouble
Sorry
I will post any found working solution
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Hi Bobby
Sorry I wasn't clear. I don't suggest you add the insulating washers they are not needed and can in some situations cause problems. So please don't add them. :)
It is pointless taking the computer apart and rebuilding it there isn't a short in the computer. As others have said the power supply would cover that without tripping the circuit breaker.
I think you said you have had problems powering the computer up you could try disconnecting all the usb devices, network cable everything except the keyboard and mouse and see if the computer powers up. When you brought the other computer to the same location did you connect everything up to it ?