# Computer won't turn on. Not sure if it's Power Supply.



## Timmo (Aug 31, 2008)

Hi, I have a small problem with my computer.
Well, It's not small. It won't turn on. At all.
I opened it because a small fan cable had come loose, and I connected it back in, but now it won't turn back on. I tried disconnecting the fan again but it still didn't work. I removed all the hardware and installed it back on the motherboard, but it still won't turn on. I'm not sure if it's my power supply. All the cables are properly in place, and a red light turns on when I connect the power supply to my wall, but the computer won't turn on at all.

Can anyone help? I know enough about computers to put one together, but I'm not very bright when it comes to naming the parts and stuff. 

(Meaning I don't know what I'm supposed to post in order to get help).


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## Stu_computer (Jul 7, 2005)

Hi Timmo, and welcome to TSF.

Let's try a power supply reset to see if that clears the probem.

Unplug the psu (the power supply) from the wall outlet.
Press in the Start button, and hold it in, for 15-20 seconds.
Now, power up and see if it starts up.

Some questions...
Was the power unplugged when you reconnected the fan?
How did you know the connection was loose?
Are there any diagnostics lights on the motherboard/case?
Does the Start button flash or change color?

Some details about the computer would also help...
make-n-model of motherboard and video card
ram, how many sticks and what type
size of psu (watts) make-n-model if you can read the sticker


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## Timmo (Aug 31, 2008)

Thanks for replying.

I did a power supply reset and it didn't work.

The power was off when I re-connected the fan.
I knew it had come loose because the fans have red, green, and blue lights on them, which had turned off.
There's two lights on the mother board. A red one that lights up when the power supply is connected and it's receiving power. And a second green light that lights up when the power is turned on. Right now, only the red light turns on.
The start button doesn't turn on at all.

Motherboard-abit kn8 Ultra
Graphics Card-e-GeForce 7800 GT CO
RAM- G.Skill DDR 1GB x2
PSU-Dynex 400W


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## vladimirb (Mar 31, 2008)

Hello and welcome to TSF...

Would be nice to try different PSU just to make sure if your PSU is good or not...
Borrow it from a friend...

Unplug all components from Motherboard and leave only CPU, RAM and Graphic card on it...


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## Stu_computer (Jul 7, 2005)

Yeah, you may have to open up the case again.

Try this first though...
Press the [Insert] key on the keyboard and hold it, then press the power on button, it may boot the system.

Before you start pulling wires off components, do a visual inspection to see if any wires came loose during the reassembly last time, also lightly press on connectors and cards to make sure their seated properly. Check that there are no screws or other metal laying on the motherboard. If all looks okay, then do a CMOS reset.


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## Timmo (Aug 31, 2008)

Didn't work. 
:\

I'm going to buy a new Power supply.


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## Stu_computer (Jul 7, 2005)

Well, it does happen occasionally that a psu will just up and quit without warning, but they usually give advance notice, like freezes and shutdowns and frying some components first--smoke and a burnt plastic smell are good indicators too.

So, the 5VSB LED comes on and the VCC LED (power-on) doesn't-not even a momentary flash?
Did you check the Start button wires, are they still secure on the PWR pins?
Pull that Start cable off and touch the pins together with a quick tap of a screwdriver tip to see if it triggers a start.

If not, then leave the cable off and try using an unfolded paper clip to short the Green wire (PS_ON) to a black wire (COM) beside it on the ATXPWR1 connector. A fast touch is all that's needed.

If that doesn't start it up then best guess is a bad psu.


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## Timmo (Aug 31, 2008)

Stu_computer said:


> Well, it does happen occasionally that a psu will just up and quit without warning, but they usually give advance notice, like freezes and shutdowns and frying some components first--smoke and a burnt plastic smell are good indicators too.
> 
> So, the 5VSB LED comes on and the VCC LED (power-on) doesn't-not even a momentary flash?
> Did you check the Start button wires, are they still secure on the PWR pins?
> ...



Well, I went to Best Buy with my comp and walked up to the Geek Squad people before I bought a new power supply, and I told them what was wrong with it plus everything that I have said so far, and they said it was a motherboard problem, due to the fact that the light on the mother board indicated that the power supply was properly distributing power to the system. 

I'm still going to try that, and see if that works. Might save me some money.


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## Stu_computer (Jul 7, 2005)

> they said it was a motherboard problem, due to the fact that the light on the mother board indicated that the power supply was properly distributing power to the system.


The motherboard has the problem.
But trust the motherboard when it indicates the psu is not the problem.

I would have never thought of that.

Does the motherboard say the cpu is okay too?

That's hilarious!!

If you have some thermal paste laying around you can try removing the cpu and all devices, power up the board for a minute then unplug again, reinstall the cpu/heatsink (with new paste) and see if it starts.
(that's an asus trick to reset a motherboard, don't know if abit does it now-but worth a try.)

Until you've tried another psu and cpu known to be good you really can't rule them out (Or tried your psu and cpu on another system) it's only a guess at this point.

http://www.arcticsilver.com/ins_route_step2amdas5.html


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## Timmo (Aug 31, 2008)

I tried following the directions in the link you provided, but I wasn't really sure on what to do. The CPUs didn't look like the one in my motherboard. Also I don't have any thermal paste, so I'm not sure what to do. If I replace my mother board does that mean I'll also have to buy another CPU?
How can I remove it correctly?


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## Stu_computer (Jul 7, 2005)

> I tried following the directions in the link you provided, but I wasn't really sure on what to do. The CPUs didn't look like the one in my motherboard.


Basically, it downloads a pdf file that describes the proper way to apply thermal paste. After you read a few for the different cpu styles you have a good idea how to apply paste to any cpu.



> Also I don't have any thermal paste, so I'm not sure what to do.


It was just a suggestion, not critical. Usually can buy a tube of Thermal paste at Computer repair locations.



> If I replace my mother board does that mean I'll also have to buy another CPU?


Depends...
If you get the exact same mobo, no.
If you get a mobo that uses that cpu socket type, no.
If it's a different cpu socket type, yes.
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Did you do the CMOS reset?

How to do a full CMOS reset on the Kn8 mobo, checklist
1. Unplug power cord, remove cover, keep one hand on metal frame to ground youself while working inside case.
2. Remove battery BAT1.
3. Move jumper on CCMOS1 from 1-2 to 2-3.
4. Remove power connectors ATXPWR1, ATX12V1, ATX4P1.
5. Leave pc as is for 5 minutes.
6. Reconnect power connectors ATXPWR1, ATX12V1, ATX4P1.
7. Reinstall battery BAT1.
8. Move jumper on CCMOS1 back to 1-2 position.
9. Reconnect power cord, hold down [Insert] key and press Start button.
10. On bootup release [Insert] key and tap [Delete] key to enter BIOS.
11. Set BIOS to fail-safe or optimum defaults.

If pc fails to boot try using a borrowed psu, or try the suspect psu in another similar pc to verify it's functional.


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## CYNiCAL2009 (May 26, 2009)

Stu_computer said:


> Well, it does happen occasionally that a psu will just up and quit without warning, but they usually give advance notice, like freezes and shutdowns and frying some components first--smoke and a burnt plastic smell are good indicators too.
> 
> So, the 5VSB LED comes on and the VCC LED (power-on) doesn't-not even a momentary flash?
> Did you check the Start button wires, are they still secure on the PWR pins?
> ...


Hi. i have the same problem. my pc wont turn on what so ever. but it does get a momentary flicker of light, HDD and PWR. you said that as if you may know the problem. but i thought it is my Mobo. thank


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## ccfinleyjr (Jun 17, 2009)

Hey, I got a intel d845gvsr mobo that wouldn't come on. Originally had a bad p/s but still didn't work w/good one. Ohmed out the turn-on switch pins on the mobo to the 20 pin atx plug (green wire, pin 14?) and no good. Then I reconnected the plug, spliced in a switch to the 14-15 pin wires, turned it on and it started the p/s. Hit the comptr start switch in front and voi-lay, it works! Probably a bad circuit lead from the electronic holding thingy-to the p/s green lead.


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