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Computer shuts off on it's own. Now it won't start...PSU???

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December 3, 2010 9:10:26 AM

So yesterday I was using my computer and it shutdown. Then it wouldn't start, it was completely dead. So I unplugged it and put it into a new socket (on a different power strip) and it started up, when I logged into windows it shut down again. :fou: 

By resetting the PSU with the on/off button from the back or plugging it in somewhere else you can usually get it to boot to the windows screen. I have two hard drives (both loaded with Windows 7 Ultimate) and I unplugged one and then the other to see if there was a problem with the HDD, but apparently it's happening with both drives. :o 


So far I have done the following:

1. Changed HDD's
2. Took apart entire computer, cleaned all parts, reapplied thermal paste and reseated heat-sink
3. Removed PSU completely and opened to check for a blown fuse or any visually noticeable problems (i.e. blown capacitor)****
4. Checked all connections including on/off switch at front panel
5. Disconnected extra components to see if there was a power shortage, I took out power for Floppy drive, DVD drive, and only ran 1 HDD.


It's a rather odd problem, the computer begins to load into windows, then stops abrubtly with a noise (HDD stopping I think) but the cpu fan keep spinning! Sometimes it will try to reboot if you let it go, but to no avail, it makes that same noise (HDD stopping I guess) and then just sits there idle. Some times you can't get it to POST (beep), but other times if you leave it off long enough it's like it forgets and then starts up just fine for while. I managed to get to the windows desktop for a bit once i was done cleaning. It's as if it has some memory :ange: 

What's really going on here guys? I suspect the PSU is in it's last stages but I'm not sure, many of you are more experienced please help.




**
VPR Matrix
Intel Pentium 4 @ 1.8Ghz
1.5 GB of DDR2 RAM
Nvidia FX5000 series GPU (bought in 2008)

Computer was purchased in 2002 so it's not worth more than a $20 PSU, but I don't want to run the risk of fire either with a cheap unit. I have a 600w PSU in my new build (Phenom II X4 955 BE, Corsair DDR3 RAM, ASUS MOBO, ATI HD 5770 1GB) I COULD technically take that out and try it on here, but I just put that back together yesterday when I installed my new Coolermaster Hyper 212 to the board :D  so i don't want to take it apart ;) 


****Not recommended, there are capacitors inside which will still hold a charge, be careful or better yet don't do this. :non: 
December 3, 2010 10:27:38 AM

Quote:
Main suspect is the hdd.Take the hdd from your new pc out and install it in this pc and see what happens.



but if there are two with seperately installed OS's (windows 7) then if I disconnet the IDE cable and power from one the other becomes master, I ran each one at a time, did they both fail? I mean what are the chances that they would both go out at the same time?

What makes you think it's the HDD?
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December 3, 2010 10:38:38 AM

I would suspect your PSU first and the motherboard as a second. Why don't you try with your new PSU if everything runs fine? However there is a risk that if the problem is in your mobo that your PSU gets damaged. But I believe that the possibility to happen something like this is low.
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December 3, 2010 10:42:44 AM

At this point you need to start eliminating things. We would all like to find the bad part without doing a lot of parts swapping, and sometimes you can do that by going to the Events Viewer, but really not usually.

Next is swapping out memory, not because it's most likely, but because it's easiest. Hard drives next, and then video cards. You may say how likely is it to be the video card? Probably not likely, but it could be, and it's easier to throw one in than to change out the PSU. Changing out the CPU is not that hard, but most of the time you don't have a compatible CPU lying around that you can try.

The last time I had one of these problems, I decided that the motherboard and processor were too old for it to be worth the trouble, and I got a new motherboard, CPU, and memory. If you look around you can find some good combo deals on Motherboards and CPUs, and the price of memory has been coming down lately.
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December 3, 2010 11:05:47 AM

Prescott_666 said:
At this point you need to start eliminating things. We would all like to find the bad part without doing a lot of parts swapping, and sometimes you can do that by going to the Events Viewer, but really not usually.

Next is swapping out memory, not because it's most likely, but because it's easiest. Hard drives next, and then video cards. You may say how likely is it to be the video card? Probably not likely, but it could be, and it's easier to throw one in than to change out the PSU. Changing out the CPU is not that hard, but most of the time you don't have a compatible CPU lying around that you can try.

The last time I had one of these problems, I decided that the motherboard and processor were too old for it to be worth the trouble, and I got a new motherboard, CPU, and memory. If you look around you can find some good combo deals on Motherboards and CPUs, and the price of memory has been coming down lately.



This is true, it's just an old computer, it can't even do HD video but suffices for the basic things, MS office, basic browsing etc



And for $200 you can build a AMD quad-core computer with a cheap MOBO and PSU that would blow this computer away, so the fix is only worth about $20-$30 considering I have a laptop and a new sort-of-high-end computer that I put together.

I have the original video card (AGP :lol:  ) so I'll try that, and try the Hard drives one more time.


What could be the problem with the MOBO? Bad capacitor? :( 
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December 3, 2010 11:07:13 AM

Quote:
There is no harm in trying.If your psu has failed completely then your pc would never start.



Correct, but a faulty PSU that turns on could also cause a problem like this. I just thought maybe someone on here could recognize the symptoms and give me a a more definate answer of what might be wrong, would save me time.


Thanks everyone
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December 3, 2010 11:09:26 AM

socratesx said:
I would suspect your PSU first and the motherboard as a second. Why don't you try with your new PSU if everything runs fine? However there is a risk that if the problem is in your mobo that your PSU gets damaged. But I believe that the possibility to happen something like this is low.



I just put that computer back together with the other PSU it sucks to have to take all the wires out again, I could try and see if the cables will reach down and I can run this MOBO hanging below my other computer so that way I won't have to pull it out
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December 3, 2010 11:22:05 AM

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

what is the risk of fire by using this PSU?

It's 350w, isn't that more than enough power for a Intel P4, intel MOBO, two HDD's, and a FX5000series Nvidia card? (that's currently what's in my system but I want to be over what I need to run this set up)
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December 3, 2010 11:25:35 AM

Quote:
Well i once had this problem.With my old pc showing black screen,refusing to boot ,slow boot.And that was becoz of my seagate hdd.Which became faulty.


Did it used to just sit there with the CPU fan running but no light on the front LEDs?

I tried both HDD's one at a time and doesn't seem to change anything... one of my RAM chips is new (1yr old kingston), video card is new (still have the old to throw back in to test)

could be the CPU, MOBO or the PSU, I doubt it's any of the others at this point...but i'll continue to troubleshoot
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December 3, 2010 12:41:37 PM

Quote:
Did you use the working hdd from you new pc?Yes,the fan used to run.



No, I just unplugged the IDE cable and the power to one and then tried the other

unless both drives have gone bad at the same exact time...which is not likely
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December 10, 2010 2:51:28 AM

Ok so at this point I'm sure it's not the HDD's


The way it's just shutting off makes me think:

CPU (since it's a 1.8ghz P4 single core it works hard)
MOBO
PSU


I will try the GPU though just to make sure that's not it
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