Power Problem

[BornStar]

I just built a new system for myself and am having a strange problem with power. When I boot up the PC, the system will run for about 5 seconds and then just shut off. If I hold the power cable into the PSU, I can keep the system running as long as I don't move my hand. As soon as the cable moves just a little, the system shuts down. The reason this is strange is the fact that this is the second PSU I've used and that's the only component that I can think of that would present a problem in such a way. The other thing I've considered is faulty grounding in my case. Below is a list of my components.

Aspire X-QPack (used the original PSU first)
Antec TruePower2 380W
A64 3200+
Zalman CNPS7000AlCu (with AS5)
Gigabyte GA-K8N51GMF-9 (6100/430)
512MB OCZ Premier PC3200 (part of a dual channel kit but one of the sticks was bad so I'm RMAing)
WD 36GB Raptor
Seagate 7200.9 160GB
NEC 3540A
Samsung DVD-ROM (don't remember the model number)

Does anybody have any ideas for me? I'm completely stumped and I don't have enough parts to start swapping stuff out.

Thanks.

 

[inspiron8200guy]

Make sure that the pins on both ATX connecters have not been pushed down so they can't make contact unless they are pushed down like you said. Can you try a different PSU? If you can, see if the problem still exists then it's prpbably something with the motherboard. Hope that helps.

 

[BornStar]

I've tried 2 different PSUs and they both yield the same result. The ATX connectors are both firmly connected to the motherboard with the clips fastened.

 

[montag451]

I had the same problem, it turned out to be a faulty mobo.....
BUT, there are many things that would cause this symptom.
First thing to try would be to disconnect everything from the mobo except psu/cpu+fan/RAM/VGA.
If the same thing happens, take out the VGA, then RAM.
If you are left with just the cpu on the board, with the same result, then take the mobo out of the case and place it on a piece of cardboard/antistatic mat and try it like that.
If there is still no beep, then the problem is either psu/mobo/cpu.

 

[FlyingPenguin]

I would suspect that you have a cold solder joint or broken foil pad on one of the power connector pins on the mobo. I doubt it's a bad or loose molex pin on the PSU since you've swapped PSUs.

If you take the board out and look at the underside beneath the PSU connector you may see that one of the pins is con soldered or the pad is broken and barely making contact. Someone good with a soldering pencil could fix it.

Another possibility is that something is shorting out underneath the mobo - maybe a mispositioned standoff or a stray screw. Doubtful though since you say PUSHING DOWN fixes the problem.

Another possibility is that you have a hairline crack in a foil trace on the mobo near the PSU connector. Very hard to spot if it's on the surface, impossible to spot and repair if it in one of the internal layers of the PC board.

One way to look for a hairline crack is to spray the suspect area with Dust Off but invert the can so it sprays the cold propellant (be careful not to burn your skin or get it in your eyes). This will freeze the foil briefly and make a crack show up easily. Again someone good with a soldering pencil could fix it if it's a surface foil trace.

If the mobo is under warranty I'd RMA it. Ask for an advanced RMA - they send you the replacement first, usually 2 day air with a credit card to cover it, and then you send back the bad one in the same package. They only charge your card if you don't return the old mobo after a certain amount of time.

Meanwhile use tape or a tie wrap to hold the PSU cable in place so you can use it.

Hope this helps...

 

[BornStar]

I've apparently mis-stated what I was doing. I'm holding the external power connector into the back of the PSU. I'm not pushing down on the motherboard.

Thanks for all of your help so far. That confusion was obviously my fault.

 

[BornStar]

Well, I took the motherboard out of my system, placed it on an antistatic bag and gave it a whirl. No luck. It turns on for 5 seconds and shuts back off. All that I have plugged into the board is the 24pin ATX power connector, the 4pin connector, the power switch and the proc/HSF. Please tell me someone else has an idea that isn't "you're motherboard's shot".

 

[inspiron8200guy]

If you are pushing the power cable into the back of the PSU then that is different. Try a new power cable.

 

[BornStar]

I've tried 3.

 

[inspiron8200guy]

3 power cabes, 2 PSU's and you still have to hold the power cord into the back of the PSU to get it to work? Have you checked to see if the pins on the back of both PSU's have been pushed in a bit so they are not all even?

 

[BornStar]

Yeah, near as I can tell, the PSUs are cool. That's why I'm so stumped on this. The only other thing that I can possibly think of is that both PSUs I've used are dual rail. But I really don't see how that would cause this problem. All new motherboards shouldn't have any problem dealing with that.

 

[montag451]

Originally posted by: BornStar18
All that I have plugged into the board is the 24pin ATX power connector, the 4pin connector, the power switch and the proc/HSF. Please tell me someone else has an idea that isn't "you're motherboard's shot".

If that is all you have plugged in, then it can only be,
psu
proc
mobo

 

[BornStar]

That's where I am at this point. Although I'm pretty sure its not the PSU because I'm on my second one. I think it's time to take a look at the processor. I suppose I could put the processor in my dad's computer but that would take a bit more time than I'm willing to spend. What are the odds I'd be able to tell if the processor was shot with an A64 with the heatspreader?

 

[montag451]

On personal experience, I would go with the 'mobo is shot'.
But, the only way is to try a known working cpu in that mobo, or
your cpu in a known working system.

Please post back with the result

 

[BornStar]

Ugh. I'm a little embarassed. I apparently had the power button leads plugged in backwards to my motherboard. The weird thing is, on both LED leads, the reset button lead and the speaker lead, the - side was black, on the power lead it was white. How does that make sense? Anyway, thanks for all of your help, everyone. I feel like an idiot.