# Solved: PC shuts down randomly (only when cold).



## pauljorgy (Apr 16, 2007)

Hi there, I need some advice to prevent my PC from shutting down. I built it with brand new parts around three years ago.

Over the past few months it has developed this problem. Here is what is happening: When the weather is cold (usually in the morning) the computer will shut down completely (like a power cut). This usually happens during startup or soon after. It may happen between 2-6 times, depending on how cold it is. It does not seem to happen at all during summer time.

I am not sure if it is related but the power button is faulty. I have to press it a few times before it starts up, this process is also more difficult when the computer is cold.

The most recent change that I have made to the hardware is to add a new CPU cooling fan. I did this a few months ago because the factory one (Intel) was getting a little noisy. The new one (Thermaltake) has a heat sensor on it, which adjusts the fan speed.

I suspect that it is either the Power Button, Power Supply or contact points for either of these. Please let me know if you have any further advice.

Thanks, I look forward to hearing from someone soon. I am nervous about taking it to a repair shop ($$$).


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## pauljorgy (Apr 16, 2007)

Further to the above details I just wanted to point out that the CPU fan is running perfectly. It has about 4 different speed settings, all of which work at the appropriate times (as determined by the heat sensor). For example - it always seems to spin at full speed when I am rendering an MPEG2 video. It then slowly comes down to low speed following the render.

It never shuts down when it has been running for more than 30 minutes. It seems it is more to do with cold than heat, thanks.


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## telecom69 (Oct 12, 2001)

I would say its definetly to do with the power button,especially since you say it never shuts down when its been running for a while,there is a high resistance connection in trouble in the button and you really should get it fixed because there will be arcing going on and it will eventually pack up anyway,it will either seize up in the on position or not come on at all ...that is what I think for what its worth


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## pauljorgy (Apr 16, 2007)

Thank you for the speedy reply. How complex is the power button? Is it a sealed part or will it be possible to see the problem? Should I entrust this job to a repair shop?

Is there a way I can test it (e.g bridging the connection with another wire). Is this dangerous territory?

Cheers.


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## pauljorgy (Apr 16, 2007)

I have just been researching the role that the power button plays in a PC (howstuffworks.com). It says that it provides a 'signal' to the power supply to get the computer going.

Does the power button maintain a 'live' part of the circuit once the PC is running? I thought it was more like a starter motor on a car (eg. it is no longer required once the engine is running).

In any case, I do need to have my power button repaired, but could it be the cause of the power failure after 2-3 minutes of the PC running?

Cheers.


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## telecom69 (Oct 12, 2001)

Its not dangerous if you know what you are doing with this sort of thing,if you dont its best to take it to a shop to do it,it shouldnt cost very much ...do not think about any bridging,it needs replacement,click on this site it might help http://computer.howstuffworks.com/power-supply.htm have to go now but if you want to post more will be back later ....


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## pauljorgy (Apr 16, 2007)

Thanks again for the reply, I still just need to have someone confirm whether the power button remains part of the 'live' circuit once the PC has successfully started up. If this is correct, I will fully believe that the button is at fault.

Cheers.


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## telecom69 (Oct 12, 2001)

Since I have no way of knowing what type of power switch is fitted to your computer I cant give you a specific answer,however if you click on this site and read it all by scrolling down it should tell you all you need to know http://www.fonerbooks.com/power.htm let me know how this ends up ......


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## pauljorgy (Apr 16, 2007)

Thanks for the link, I checked the flow chart. I am 99% sure it is not the power button. The computer works perfectly all day - after starting it 3-4 times in the morning. When it is warm it behaves normally with the power button (on & off).

Is there anything else that could be causing the problem?

It is almost exactly like the engine of an older car - there is no problem at all when it is warm, however in the cold it takes a few attempts then it works perfectly.

I need to try another solution.


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## Rich-M (May 3, 2006)

I think it is the power supply itself. Unless the button is broken off or stuck, I have never seen a power button really cause any problems.


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## pauljorgy (Apr 16, 2007)

I might see if I can find another power supply to run the system. I will let you know how it goes, thanks.


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## pauljorgy (Apr 16, 2007)

I have just put another power supply in (temporarily). It is working fine, the next cold morning will be the real test! Also the power button is working perfectly too.

Now I would really appreciate some advice on what sort of power supply to buy (this one comes out of my friends computer). It is an ATX ('1' I think) P4, currently 300W.

There are a lot of cheap PSU's out there, what are some of the better brands to go for?The one that I have been using is branded as 'Switching'.


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## Lil Chris (Jan 28, 2003)

Stick to one of the better makes like enemax antec seasonic etc,looking at your spec something about 400w will probably be ok unless your thinking of upgrading your graphics


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## Rich-M (May 3, 2006)

Avoid the "cheaper brands" and generics at all cost. If it isn't Antec, Enermax, Thermaltake or Sparkle, I don't buy it. And I agree 400 watts is minimum these days.


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## pauljorgy (Apr 16, 2007)

Thanks heaps for the advice. I have found one that I think I will buy, here is the description:

_Thermaltake Purepower W0008RAC, 420W ATX PSU, Active PFC, Silver, Retail, Auto Control_.

It says that it is 'Pentium 4 Compliant'. Is it possible to use this on a Socket 775 mobo & CPU? I am looking at upgrading these parts next year. At the moment I am using a Socket 478.

Thanks again.


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## win2kpro (Jul 19, 2005)

If you are going to upgrade the processor and motherboard next year I would seriously consider a power supply of about 550-600 watts so you won't have problems if you are going to upgrade to a PCI-e video card.


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## Lil Chris (Jan 28, 2003)

Yes I would agree with Win2kpro that if your thinking of upgrading motherboard and going to core2 I would get a 500w/550w PSU.It beats having to upgrade again,make sure that it has the pci express connectors and 24pin mb connector,most new ones will and like we said stick to the top makes Enermax,Seasonic,Sparkle,Antec and you will be ok.


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## pauljorgy (Apr 16, 2007)

This may seem like a silly question to you - can I use the same PSU to plug into different systems - do they all have the same connecters?

I notice the descriptions sometimes say 20 or 24 pin - what do I need to know about this?

Put simply, if I buy the latest 600W PSU (for future upgrade possibilities) - will it still work on my current set-up? If so is there any 'connector type' that I need to specify?

Thanks.


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## Rich-M (May 3, 2006)

Excellent I have 6 of these in use now.


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## win2kpro (Jul 19, 2005)

Buy one that says 20+4 main connector. These can be used with 20 pin or 24 pin motherboards.

A 600 watt that fits your case will work with your present motherboard. In all my builds I always as such "over build" to be prepared for future upgrades.


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## pauljorgy (Apr 16, 2007)

Awesome, that is a great help. The website that I am browsing specifies an 'ATX Version' - either 1.3, 2.0, 2.03 or 2.2. Do I need to know anything about this? I do not know which one I have (I suspect it will be the oldest/cheapest).

Thanks for the info about the 20+4 pin.


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## win2kpro (Jul 19, 2005)

ATX ver. 2.2 is the latest revision.

Here are the specs for ver. 2.2

http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf


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## win2kpro (Jul 19, 2005)

If you like ThermalTake (which are excellent power supply's) here is one that should serve you well. Plenty of power, reasonable price, and any connector you should need. Also 3 year warranty.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817153033


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## pauljorgy (Apr 16, 2007)

Thanks for all the advice. I briefly read the ATX article from formfactors.org and understand the basic differences now.

Also, it is a reasonably cold morning here and my computer is running fine (with my friends PSU). The power button is working perfectly.

Now it is time to go shopping! I have found the PSU that you (win2kpro) have suggested at my online retailer here in NZ for $200NZ - which is on the high side of what I wanted to spend, however it should keep things future proof.

Thanks again, I am happy that this issue is resolved.

Well done to the team at TSG - keep up the good work.


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