Computer Wont Turn on!

Juice Box

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Nov 7, 2003
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Ok, i just got done modding my PSU wires and now when everythigns plugged back in, the computer will not turn on. The lights and everthing turn on for a half second when i hit the switch, but it does not fully power up. I did not mod the 20 pin ATX conenctor, but i did do the 4 pin one, and it is possible i switched the two yellow and or black ones. I didnt think the order made a diff cause id think they would me them diff colors if they did. Do you know a reason it will not boot up? thanks
 

Viper96720

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Jul 15, 2002
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Huh you switched yellow and black? Course it won't work if you did that. Suprised your mb isn't screwed.
 

Juice Box

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Nov 7, 2003
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Also, I did try to remove one of the 20 pin ones and it kinda got spread out a little, its one of the corner ones, I dont know if it spreading out will make a difference or not, But what puzzles me is why it turn on for that half sec and then goes off.
 

Juice Box

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Nov 7, 2003
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No, i didnt switch the yeellow and black, i put the two yellow and two black in the rights spots, im saying i may have switched the two yellow with eachotehr as well as the two black.
 

mechBgon

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Oct 31, 1999
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Here's a photo of the four-pin power plug: link Note the position of the latch on the edge of the plug and compare that to yours, see if the wires are in the right holes or not.
 

Juice Box

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Nov 7, 2003
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I also must admit that the two inner black wires from the 4 pin molex may have been switched as well cause i assumed that theyd be diff colors of it mattered. But i dont think thats the prob cause the lights are attached to the molex and they turn on for a sec.
 

Juice Box

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Nov 7, 2003
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The wires are in the right holes but what im saying is that the two yellow my be inverted, and the two black might be too, im not sure if that matters though.
 

stevty2889

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Dec 13, 2003
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Have you tried booting up with just the basics(video card, ram, CPU w/HS and Fan)? You might also want to try another power supply. What kind of mods were you trying to do to your PSU?
 

Juice Box

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Nov 7, 2003
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Its also wierd cause i have to unplug the PSU and re plug it for the lights to go on when i hit the power switch. Im wondering if the PSU han auto off feature to prevent a blowout or something, do you have an idea?
 

Juice Box

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Nov 7, 2003
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Ok tried booting up with basics and nothing, All i saw was the boot light blink real quick but then turn off.
 

mechBgon

Super Moderator<br>Elite Member
Oct 31, 1999
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Originally posted by: digitalsnare
I dont have another power supply.
Hmmm... well, take a look at this diagram of the main ATX plug and note the position of the latch, which is on the right edge. Comparing that to your ATX cable, which wire seemed to have a stretched-out connector, which corner?

Your suspicion was correct about it not mattering if the two black wires got swapped with eachother. They're connected to eachother inside the PSU, it's the same either way.
 

Juice Box

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Nov 7, 2003
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Ok i fixed the 20 pin spreaded out pin and now I have no idea why this thing wont turn on. Is there any more suggestions?
 

mechBgon

Super Moderator<br>Elite Member
Oct 31, 1999
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Maybe you have a wire in the wrong hole in its plug somewhere. Try unplugging all of the four-pin drive plugs from the drives, lights, fans and anything else (and unplug the drives' data cables too). It would probably be smart to leave them that way until you're sure what's the matter here, by the way.

If the video card requires a power cable, check that it's got the red (5-volt) and yellow (12-volt) wires in the correct holes in the plug (and check the rest of the plugs too, of course).

Now, your board has a standby power LED in the center of its bottom edge, correct? That's lit when the board has power. If you turn the PSU off, then turn it on again, that LED lights up. Then you try to actually start the system and it dies. Does that light stay lit, or does it go out? I'm trying to determine whether your power supply is actually turning OFF like it's tripped an internal circuit breaker, or if it's the motherboard pouting about something. So tell me if that LED stays on after the board has died. Watch it for about 15 seconds, since the board's capacitors could power it for a while.
 

Juice Box

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Nov 7, 2003
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No, the standbby light is always on, it goes off only when i turn off the PSU. I already have un plugged everything i dont need.
 

mechBgon

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Oct 31, 1999
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Ok, that's interesting. It sounds like it's the motherboard, not the PSU, that's cutting the power. You didn't take off your heatsink along the way somewhere, did you? Because one reason an AthlonXP system will cut power is that the CPU is not able to effectively transfer heat to the heatsink. You might want to review this guide really quick if you did take it off, and confirm it's oriented the right way and has a fresh application of thermal grease.
 

Juice Box

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Nov 7, 2003
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No, i did nothing with the CPU heatsink. I left the mobo in the case. So, do you know anything else it could be?
 

mrakman

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Dec 11, 2001
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try taking out the mobo and see if it turns on when it is NOT connected to the case...thats how i figured out whats wrong w/ mine (and it was a screw pushing in part of the mobo where hte power supply connects to it)
 

sharq

Senior member
Mar 11, 2003
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Can you borrow a power supply to test with? Or try buying a cheap PSU to test with (a 250watt would even do just to see if the computer posts with the basics).
 

Juice Box

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Nov 7, 2003
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I guess thats what i have to do cause i have no other choice, I took the PSU out of the case and did the green wire jumper thing and it wont turn on then either, so I have no idea what the problem is!