Dead PC

Growltiger

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I came back from being away, plugged in and turned on my main PC (Asus motherboard, i7 920 CPU, 12GB) and nothing happened. Silence. No fans or disks turning, no beeps.

I confirmed the power cable was OK and was delivering power.

On opening the case I could see the little lights illuminated on the motherboard on the switches to turn the power on and off, and to reset. Pressing the on/off switch on the board did nothing.

There seemed to be a very slight burning smell from the power supply (700W Fractal Design).

So my hope is that all that is wrong is the power supply. I ordered an 850W Corsair similar to one in my other main machine (which is far far away so I couldn't swap over for a test).

It worries me that the power supply was still giving power for the LEDs on the motherboard switches, indicating it is not totally dead.

Did I make the right decision?

Do you think the new power supply will solve the problem?

If not, what shall I do next? As you may imagine I'm reluctant to buy a new motherboard, CPU and memory, just to find out where the problem is.

At some point when I replace my oldest machine I will have two similar ones here so I can swap components to diagnose problems. It is fairly easy to diagnose problems once they manage to make a beep, but when they remain silent it is more difficult.
 
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Check the MoBo for any burns.
Check the power supply and see if it's at 220 or 120v.
How often do you clean your system?
More dust in the fans, the harder it has to work.
 

Growltiger

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No visible burns that I can see.
Power supply supports 115-230V, 50/60Hz. (230V here). No voltage switch.
I clean it now and again. It was recently cleaned and still looks clean. Nothing is clogged.
The power supply smells worse this morning, which is encouraging.
The new power supply should arrive tomorrow.
 
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Sounds like it is the power supply if there's continued smell.
Hope everything works out fine with the new power supply.
 
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PS's produce several different voltages on several "Rails": +12v, +5v, +3v

One of the Rails has probably failed, most likely the +12v...

If you open the PS you will probably find a burnt/burst capacitor, the most common
reason for a failed Rail... If you had NO power (lights) then it would have been the
power coil...

Just my off the hip guess... :wink:
 
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My guess would be the power supply or at least part as you are still getting a trickle to enable you mobo lights illuminated - which is a little strange in itself. Burning smell however slight from PSU indicates all is not well here

Does the PSU fan spin up correctly?

As you have ordered a new PSU I would be tempted to just replace and check all is well.

If you want to check the old PSU there is the paper clip trick or use a multimeter but these tests do not really prove that the PSU is good as it really needs testing under load.

Please check the following is correct before proceeding as these are from some old notes I made years ago!

Multimeter

Yellow wires should be 12 volts
Red 5 volts
Orange 3.3 volts
Blue wire -12 volts
Purple wire is the 5 volt standby.
Grey wire is really important as it send a control signal from PSU to mobo
It should go from 0 volts to about 5 volts within a half second of pressing the case power switch. Without this the computer will not boot. Tolerance accepted +/- 5%

Paper clip test
Plug the bare PSU into the wall.
Insert one end of a paper clip into the green wire pin
Insert the other end into one of the black wire pins beside it. This is effectively how the case power switch works.
Turn on the PSU and if the fan does not spin up then you have a deceased PSU on your hands

EDIT ATX pin out diagram just in case
 
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Growltiger

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No, the PSU fan doesn't move.

Thanks for all that information. This loooks fun...

I installed the paperclip. Still no PSU fan.
Then I measured the voltage on every pin and the only one with any voltage was pin 9, which was +5V as it should be.

So it looks as if it simply is not turning on, even when there is no load.

It doesn't look possible to open up the PSU and even if I did I'm not sure I'd see much.
 
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Sounds like a PSU issue to me, too - but while you're in there you may want to pull the CPU and check it and the socket out visually for scorch marks and melted pin tips. This has been reported in a fair number of cases, usually, but not always after overclocking. I don't think this would cause the issue you've seen, but it might be prudent to check if the hassle isn't too great. You have to check the pin tips with a magnifying glass as the malformed tips are hardly visible, but are often enough to cause misalignment and subsequent mayhem!
 
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Sounds like PSU. You should consider getting a power supply tester. I know it won't help you this time, but they come in handy.

There were a couple of times that I couldn't detect the issue via a multimeter. All of the voltages were within tolerance, however the PSU tester came back with a bad ground. Plus, its just so much faster to plug in the entire motherboard power connector and glance at the LED's as to what's working or not.
 
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No, the PSU fan doesn't move.

Thanks for all that information. This loooks fun...

I installed the paperclip. Still no PSU fan.
Then I measured the voltage on every pin and the only one with any voltage was pin 9, which was +5V as it should be.

So it looks as if it simply is not turning on, even when there is no load.

It doesn't look possible to open up the PSU and even if I did I'm not sure I'd see much.
Dead PSU then most probable although it is possible that the PSUs may use a constantly on fan or heat controlled or one that works only works when load demanded?

No idea what you would find if you did open the PSU, would there be user replaceable parts?. One thing I would say is be careful if you do as the capacitors would need discharging properly - it is rather disconcerting to see a large flash and hear a large bang and then find you have welded your screwdriver to the capacitor :smile:
IMHO it is not a good idea to try and repair a PSU (and may be even dangerous), even electronics techs will likely think it a waste of money and effort and consign it to being a whizzer (the noise it makes as it flies to the recycle bin!).

What about the warranty on the dead PSU, most offer a few years and if you are lucky well...?
 

Growltiger

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Sounds like PSU. You should consider getting a power supply tester. I know it won't help you this time, but they come in handy.
Great idea, I just ordered one. If I still have problems with the new supply, at least I will be able to check it is OK. And if I don't, well it will still be useful some time.
 

Growltiger

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Dead PSU then most probable although it is possible that the PSUs may use a constantly on fan or heat controlled or one that works only works when load demanded?

No idea what you would find if you did open the PSU, would there be user replaceable parts?. One thing I would say is be careful if you do as the capacitors would need discharging properly - it is rather disconcerting to see a large flash and hear a large bang and then find you have welded your screwdriver to the capacitor :smile:
IMHO it is not a good idea to try and repair a PSU (and may be even dangerous), even electronics techs will likely think it a waste of money and effort and consign it to being a whizzer (the noise it makes as it flies to the recycle bin!).

What about the warranty on the dead PSU, most offer a few years and if you are lucky well...?
I'm not going to risk my life by opening it, and it looks like it would need a large can opener. (I remember as a teenager getting a wonderful arc from my screwdriver to the inside of a colour TV).

I don't want another PSU like that one so I'm not even checking the warranty. It was 3 years old.
 
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Richard,
One thing I never skimp on is the PSU. Back in the old days, I've had cheap ones die and take CPU's and MOBO's with them. I've had good luck with "PC Power and Cooling" products as well as "Olympus" and "Coolmax" units for lower wattage requirements.

Tony,

Thanks for the ATX PSU pinout. It may come in handy some day :rolleyes:.
 

Growltiger

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I like the status reporting from the courier company:
Your OVERCLOCKERS order will be delivered today by Andy, your DPD driver, between 15:21 - 16:21.
The last time I had a delivery from this courier company I spotted the vehicle waiting at the end of the drive. I went to it and asked the driver if he was looking for my house. He replied "No, I just have to wait two more minutes and then I can deliver to you. I'm ahead of schedule and I'm only allowed to deliver in the time slot allocated." Two minutes later he handed over the parcel.
 
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Richard,
One thing I never skimp on is the PSU. Back in the old days, I've had cheap ones die and take CPU's and MOBO's with them. I've had good luck with "PC Power and Cooling" products as well as "Olympus" and "Coolmax" units for lower wattage requirements.

Tony,

Thanks for the ATX PSU pinout. It may come in handy some day :rolleyes:.
That's what happened to my first PC... Power supply overvolted as it died and
fried the MB and CPU... Now I only use PC Power and Cooling with the large,
big honkin-high amperage, single +12v rail... :wink:
 

Growltiger

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Thanks everyone for your advice and support.

The good news is that the new power supply made it all work. Nothing had been damaged.

(No thanks to the courier company who lied and claimed the item had been refused by me. I had to drive all the way to their depot to get it. I live in the middle of nowhere so the drivers don't like to come here.)
 
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Thanks everyone for your advice and support.

The good news is that the new power supply made it all work. Nothing had been damaged.
Glad you got it sorted.

(No thanks to the courier company who lied and claimed the item had been refused by me. I had to drive all the way to their depot to get it. I live in the middle of nowhere so the drivers don't like to come here.)
A CCTV camera on the front porch eliminates this problem really fast!:smile::smile::smile:
 
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.....I've had good luck with "PC Power and Cooling" products as well as "Olympus" and "Coolmax" units for lower wattage requirements.....
Corsair and Seasonic are my picks. Here is a nice ratings list. Power Supply Ratings I try and stay in tier 1, 2, 2b. Though I do like the little Corsair CX430. Nice little unit for a basic desktop.

Which 850 did you get Growl? You do know that's more power than you probably needed right? (or do you have some big gaming gpu in there?)
 
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