# Computer Won't Turn On



## kevinski (Jul 14, 2003)

Upon returning home from work, I noticed that my computer tower was off. So, I pressed the power button. Nothing happened. The power supply is working just fine, because the motherboard light is on. What could be the problem?


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## Guest (Aug 23, 2003)

Just because the green led is on doesn't mean the power supply is good.

Shut off the machine with the switch on the power supply and unplug it. then plug it back on and turn on the switch and try powering up the PC again.


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## kevinski (Jul 14, 2003)

*Switch on the Power Supply?*

If you're referring to the surge protector, I've already tried that. Upon unplugging the computer, the motherboard light went off. Everything else that was on the same surge protector works just fine. Now, if you're referring to a switch built into the power supply inside the case, you'll need to educate me on how to find this switch, because I didn't know there was a switch there.


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## Guest (Aug 23, 2003)

Isn't there an on/off switch on yuor power supply right above or below where the power cord plugs in?

How about some specs on your machine?


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## Volt-Schwibe (Jan 12, 2003)

*heh*

actually not all of them have that switch, i know none of mine do...

but powering it down, and then unplugging it is the equivilent to flipping that switch off.

~BoB~


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## kevinski (Jul 14, 2003)

*Specs*

1.7 GHz Pentium 4 Processor
64 MB GeForce2 MX 400
40 GB Hard Drive
Windows XP Professional

I'm not really sure what other specs you'd like, so just lemme know.


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## Guest (Aug 23, 2003)

You know the button that you turn the computer on with? Well take a look inside the case and see if the wire that comes from it is connected properly to the motherboard. Then put your finger on the on/off button on the front of the case and give it a couple of sharp jabs. These have been known to get sticky and loose a connection now and then.

If none of this works I would try another power supply first.


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## kevinski (Jul 14, 2003)

*Okay…*

The wire is connected to the motherboard just fine. And - like I said - the motherboard light is on. I've tried jabbing the button harder, but the computer still won't turn on. Do you seriously think I should get a new power supply if the motherboard light is on? And how much would one cost?


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## Guest (Aug 24, 2003)

See if you can borrow one? Don't you have any close friends that have computers?


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## Volt-Schwibe (Jan 12, 2003)

*hmm*

i would suggest a different power supply as well.

one can usually be found for between 30 and 40 bucks.
unless you go way budget or high end...

and what light are you referring to?

some motherboards have an led on the motherboard itself, but i am not sure you arent talking about the light on the tower.

when you have it unplugged, then plug it in, and hit the button, does the light come on?

if so, are the fans/hard disk spinning?

if not, do they even twitch?

does it make any odd noises?

will the cd-roms open if you try to open them?

these are all the things i know would be helpful.

chances are, the supply is dead, or there is a peice of hardware thats halfway plugged in. (or fried)

try a new power supply before you rip into it too far though.

after that, you might try speedo's fail safe plan, and try to start it with the mobo laid out, only cpu/fan, and ram, and video, and see what it does.

then one by one, put stuff back and see what stops it.

ive seen a fried pci/agp card stop a machine from booting, as well as bad cpu.

~BoB~


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## kevinski (Jul 14, 2003)

*Removing a Power Supply, etc.*

Well, I'm using my cousin's computer right now. Would I just be able to remove his power supply and try it in my computer? Mine's a Dell, and his is a Gateway. I mean, are all power supplies compatible with all computers?

As for the motherboard light, yes, I'm referring to the LED that's right on the motherboard itself. I have the case open, and nothing else responds upon pressing the power button. The motherboard light is on as soon as I plug in the computer. No fan or hard disk response, no odd noises, no CD-ROM functionality, no nothing. I'll try the other power supply, assuming that it'll work with my computer. All I need to know is whether or not it'd be compatible. I've never replaced a power supply before.


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## Guest (Aug 24, 2003)

They should be similar enough to get the machine to boot if that truly is the problem. Thats all you need to do is get it hooked up to the motherboard and see if it fires up.


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## kevinski (Jul 14, 2003)

*Problem*

There's a small problem with substituting my cousin's power supply for my own. There are two sets of cables that need to be connected to either motherboard. While one set will hook up properly, the other set isn't identical. Mine accommodates 4 pins, whereas my cousin's accommodates only 2 pins. Do both sets of cables need to be connected properly, or would one set suffice?


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## kevinski (Jul 14, 2003)

*One Quick Question*

By the way, there was something confusing me about the previous posts in this thread. If the problem IS the power supply, is it still possible for the motherboard light to be one? I don't exactly understand the workings of the power supply in relation to every component within the tower, so could someone explain how the motherboard light would be on if the power supply was bad?

Also, any tips on what I could try if I can't find a power supply that'll connect to my computer (without having to buy one)?


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## kevinski (Jul 14, 2003)

*Power Supply Operational*

Well, the power supply works just fine. I attached the one cable from my cousin's power supply that would connect correctly to my motherboard and plugged the computer in. The motherboard light came on again, but nothing happened upon pressing the power button. Then, I connected the one cable from my power supply to my cousin's motherboard and plugged it in, then turned on the computer. The fan on the power supply started spinning. Definitely a good sign. Now that the power supply has been confirmed as working, should my next concern be the power switch itself?


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## x5dr (Aug 3, 2003)

*Well, I'm using my cousin's computer right now. Would I just be able to remove his power supply and try it in my computer? Mine's a Dell, and his is a Gateway. I mean, are all power supplies compatible with all computers?* 

No they aren't...and probably won't work together...Dell/Compaq/Gateway/HP/etc. have proprietary parts, NOT ATX, and are not interchangeable....you could do damage if you are even able to get it to powerup.

ATX is a standard that manufacturer's use so all parts will fit together...

I've also seen people destroy their PC by leaving it on 24/7. They leave and the fan goes out on their PS and overheats.


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## johnwill (Sep 26, 2002)

"_Destroy their PC_"? That's a little extreme.  I run four systems here 24/7, and even though I've had several fan failures, all the machines are alive and well. If you don't have any additional cooling and the P/S fan goes, it could take out the P/S, but that's a long ways from destroying the PC, it's just a replacement part. Most new PC's come with a monitor that will shutdown the system if the temperatures get too high, which will minimize the possibility of significant damage from overheating.


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## Guest (Aug 25, 2003)

Well my next suspect would be the CPU! There have been occasions when you could just re-seat it in the socket and it will boot right up afterwords.

But before you go and try that get a light in there and take a real close look at the capacitors and see if any of them are leaking or bulging?


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## x5dr (Aug 3, 2003)

just a warning because it happened to a neighbor's...dang...I've taken PC's out of the trash that were submerged in water that I got up and running but I wouldn't recommend washing your PC.


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## Volt-Schwibe (Jan 12, 2003)

*hmm*

and yes, even if a power supply is bad, it can still power the little led on the motherboard. the power supply isnt as simple as a battery, it in fact has several seperate branches that can die, and if one of these lone cowboys dies, the others may still work, so it is possible for the 5v or the 3.3v to die, and im sure that light could still work if only one branch or the power died.


the light on the board is simply to let you know that it has some sort of power. yet, it doesnt mean it has all the branches of power that it requires to start.

but, seeing how you have tried a different power supply, i would suggest you try and reseat your cpu and ram. also, the video card and other cards can sometimes be partially unseated, and they can also stop the machine from booting.

~BoB~


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## johnwill (Sep 26, 2002)

I have a power supply sitting on my bench that fits your description!  I'm working on a customer's PC and the next morning it was dead as a doornail, no action when I push the button! Took the supply out and fired it up on the bench, and I'm missing the +5VSB voltage, so the PC can't start the supply. If I short the switch leads, it all comes on, except for that voltage...


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## Volt-Schwibe (Jan 12, 2003)

*heh*

alot of people dont even realize that the power supply is really like 5 or 6 power supplies inside...

get a schematic for a pc power supply, and you will see all the different districts on the board. those are the different branches for different voltages and wattage loads.

a shematic for a simple power supply (like the transformer type that power things like walkmans, and your pc speakers, and a cordless phone for example) would only have one main district.

~BoB~


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## kevinski (Jul 14, 2003)

*Processor Reseated*

Well, I reseated the processor. It really didn't change anything. Everything's properly seated, in fact. Getting back to the power supply, though, the fan didn't even kick on in my computer, whereas it did in my cousin's computer. Now that the processor has been verified as properly seated, what should I do?

I'm trying to figure out what the problem could be. Honestly, I thought maybe it could be the power switch, but I couldn't understand why it would've turned off in the first place. Exactly what could've disrupted the operation of the computer in order to turn it off, yet have nothing to do with the power supply? I mean, it doesn't even respond in the slightest when I press the power button, so shouldn't it have something to do with the switch?


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## Volt-Schwibe (Jan 12, 2003)

*hmm*

i am still fully considering the power supply to be the problem, although i am not saying it definately is.

that is really the problem with a proprietary machine, nothing is made to swap.

if the fans on yours didnt come on, whereas the fans on the other one did, then i would still consider that your power supply may be bad.

you just might have to pay a tech to bench test the supply.

unless you have a tech in your area that is good and honest and cheap, it might be cheaper to buy a new supply instead.

~BoB~


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## Guest (Aug 26, 2003)

Well I'll have to say that it's really looking like it could be the power supply. I tend to go along with BV that getting it tested might be a good idea but if you have to pay to get it done you would be better off putting the money into a new power supply.


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## kevinski (Jul 14, 2003)

*One Concern*

I opened up the power supply, and I noticed that there was some sort of white…something…all over the place on the inside. Now, I'm not exactly sure if it's actually a problem or not, as I tried to scrape some of the substance off with no luck. I could take a photograph of the inside to show you what it looks like, if that would help.

Now, it's not as though I'm questioning anyone's knowledge of computers, but you guys DID note that my power supply worked in my cousin's computer, while my cousin's power supply didn't work in my computer, right? I mean, his power supply worked fine in his computer, but it wouldn't do anything in mine?


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## Volt-Schwibe (Jan 12, 2003)

*hmm*

i didnt actually notice you said yours worked in his.


that does change some things.

still could be a fried cpu or ram stick.

still might be a fried pci or agp card...



but yeah, i hadnt noticed.

~BoB~


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## kevinski (Jul 14, 2003)

*Fried Anything?*

I've had a fried processor before. Actually, twice before. Thing is, though, that it never prevented the computer from powering up. Sure, it wouldn't boot properly into Windows, but it'd still at least respond by TRYING to boot. I'll check all of the cards, though, to make sure they're properly seated. Also, I'll try removing one of the RAM chips at a time and trying to power up the computer with only 256 MB of RAM. I actually have a total of 512 MB.


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## Guest (Aug 26, 2003)

Did you actually get your cousins computer to boot to windows with your power supply?

That white stuff probably leaked out of one of the caps!


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## kevinski (Jul 14, 2003)

*Nope*

I never tried to get it to boot into Windows. Remember how I said that there were two connections that go to the motherboard on each power supply, and that the one wouldn't fit on the other computer? I highly doubt I could get full functionality out of my cousin's computer if the power supply wasn't fully connected. I could probably hook up the drives and such, but couldn't the second connection's absence pose a problem for booting correctly?


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## kevinski (Jul 14, 2003)

*Caps*

By the way, I couldn't find a broken cap or anything. That doesn't necessarily mean there isn't one, though. Still, maybe I'll try to boot my cousin's computer completely with my power supply, despite it not being fully connected.


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## johnwill (Sep 26, 2002)

I have zero faith that you have adequately tested the P/S, I think you really should do a proper test of that before you panic.


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## kevinski (Jul 14, 2003)

*Adequately Tested*

So, by 'adequately tested', do you mean I should try booting my cousin's computer with my power supply, or do you think I should have a professional take a look at it?


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## johnwill (Sep 26, 2002)

Well, I would want to see the P/S actually power up a system before I declared it working. I have a P/S sitting my bench right now, and if I plug it in and short the two power contacts, it appears to work. +5 and +12 come out right in spec. Upon closer examination, I see that +5VSB is not functional, which will prevent the P/S from actually powering a system.


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## Volt-Schwibe (Jan 12, 2003)

*hmm*

ok, i am going to try to clear this up...

the wires on the power supply that plug into the motherboard...

im not sure what you meant by two different ones...

as far as power wires, some of them have a single plug with approxamately 18 wires, and some have a set of two plugs with 6 or so each...

on top of that, some have a small wire set of wires that come out of the supply, and plugs into the board, and this one has two or three wires. this on plugs into the board to control the power supply fan.

on top of those, they all have the wires that power the hard disks, floppies, and cd-roms.

older ones also have a set of 4 wires that go to a physical switch on the front of the tower, whereas newer ones have a small set of wires from the motherboard that go to a set of soft off switch and reset switch.

what type is your supply, and what type is your cousins' supply?

if your supply actually made his turn on, and actually showed the bios boot screen where it tests ram and stuff, but did not do the same thing on yours, then i would maybe assume that it might be a working supply.

booting all the way into windows is a better test though.

you mentioned some white stuff on the power supply board, but im not sure this came from the caps. usually a swollen leaky cap will be covered with a brown resinous substance, almost like terriaki sauce. i did say usually.

sometimes oxidization can form on a circut board, if the unit has been exposed to moisture.

you mentioned having a way to take a picture...

perhaps you could set your power supply, and your cousins power supply next to each other and take a picture of the difference in the cables you mentioned.

it might also help to see a pic of the plugs on his and the sockets on your board that his plugs wont fit into.

again, this is why i hate stuff that is made proprietary, like dell, and gateway, and sony, and hp.

i like things that are swappable.

now as far as a fried cpu keeping the machine from booting, i have seen some fried cpu's simply not go past the boot test, and i have seen some not even start at all. (meaning the monitor never showed anything at all)

i have also seen ram sticks do both of these, and pci cards, and agp cards, so you shouldnt ever simply say that it cant happen.

~BoB~


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