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Weird Issue

Last response: in Systems
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July 25, 2010 5:27:15 AM

Hey Guys,

Okay I'm new but I have done my homework, have read close to 100 threads now before posting.

First off, here is my specs (yes I know it's old):

MSI K8N Diamond Plus
AMD Athlon 64 3700+ Socket 939
OCS Gold Edition PC4000 Dual Channel DDR(500mhz)
Silverstone 560Watt (but more importantly, 38Amps on 12v rail)
2each Geforce 7600GT in SLI

Okay, now as I said I have done much research and think I have a faulty mobo, not positive though. I need to pinpoint the problem and also figured out WHY this happened.

My computer, when pressing the power button, starts up for 1 second then shuts off. All fans spin, etc, but no beeps (presumable because its only on for 1 sec). After this I see that the LED on the back of my PSU is red, when normally it is either Green or Orange. I have found out red might indicate circuit protection has been initiated.

Okay, so maybe I have a short.

I pull out the components to do a bench/breadbord test. I start with the bare essentials. I swap out ram sticks, one at a time to see if they might be bad. I try another socket 939 processor. Still same problem, starts up for 1 sec then immediately shuts down.

I try jumping the pins for the power switch, thinking the switch might have been faulty, but it is not, same problem. I try jumping the 'green' wire and a ground on the 24 pin mobo connector, to test the PSU. It comes on and stays on until I disconnect these jumped pins. So it would appear the PSU might be okay (was not a load test, but still...)

Now I am down to possibly the mobo, I inspected with a flashlight and magnifying glass, no bad capacitors, no burnt components that I can tell.

Thinking my next step is to dive into PSU testing with my multimeter, but I will have to read up on that first.

Here is the kicker: When I disconnect the 8pin CPU connector (the one that plugs into the mobo to give the CPU its power), when that is DISCONNECTED, then the computer will power up and stay powered on. Once plugged back in, however, and tried to start it does the 1sec on then dies thing.

So, i guess there might be short circuit in the cpu/mobo/psu wiring somewhere, just not sure where.

Seriously guys, anyone have any ideas as to what could this be?

More about : weird issue

July 25, 2010 5:50:04 AM

Seems like you have isolated the problem to 3 possible causes. A bad PS, CPU or MB. If you have another computer available swap the PS from it to this one. A PS swap is the easiest. I suspect it is the PS.
July 25, 2010 7:38:40 AM

Correct. Although I have tried 2 different known good CPU's, so I think it is either the PSU or mobo.

In either case I will have to purchase a new one to swap it out, as my friends don't have gaming PC's... This is my dilemma I don't really want to purchase parts to 'shotgun' them in until I know for sure which part is bad. At this point it seems just as likely that it is the PSU as it is the Mobo.....

Just strange that it was working perfectly fine and now nothing. I have never had a computer not even willing to power on in this way before. I was sad to find that it does this even on the bench, hoping to solve it as merely a grounding out of a mobo mount screw. Something is still shorting out it would seem...

Has anyone else had this issue? I found tons of threads on this website and others, but many were unresolved, with the original poster just trailing off (he talks about his problem, gets a few replies, then you don't see anything else again in the thread) so I don't know if it got resolved or if they just threw in the towel and bought new components...
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July 25, 2010 4:42:24 PM

If a PS component has gone bad only under load, you will get the actions you are observing. If you have access to a PS it does not need to be anything special. You just want to see if the system will boot normally. You might try using your PS to try to power up a friends system. However if it is a bad PS you run the risk of damage to the other system. Protection circuits are not foolproof. Another possibility is to pull the PS and take it to a local Comp. repair shop and ask it to be tested under load. You can always buy a new PS from a company with a solid return policy and try the swap that way. I fund a review of the PS marked Aug./2006. So it is not exactly new but not very old either. In short, you now have 2 possible culprits and the PS is the easiest to check out. GL and pls post what happens.
July 25, 2010 5:02:30 PM

Thanks for the replies guys. It would seem there is no easy way out that will give me that warm and fuzzy feeling. I think I will buy a PSU for testing and return it if the problem is still there. Man, that would suck if I bought a brand new faulty PSU then I would incorrectly assume the mobo is bad. But what are the chances of that...
July 26, 2010 4:28:55 PM

depending on who you baught it from, anyware from 1in5 to 1in500
July 26, 2010 5:27:32 PM

Yeah, well I think I figured out why most of these threads regarding this issue kind of fizzle out with no resolution.

I kind of decided that now is the time to upgrade since it is more than likely the mobo took a crap on me.

Can't buy a socket 939 mobo anymore for a reasonable price (mine brand new now is over $200). So with that money why not spend less to get something modern and faster?

So with that logic I have resorted to basically building a whole new computer because of 1 failed part. Meh, it was probably time to upgrade anyways.

Thanks for the replies guys and just know that this was never a fixable problem but was solved in a way (buying a new rig).

Phenom II x4 955 BE
MSI nForce980i SLI mobo
Corsair 750w PSU (CMPSU-750TX)
ADATA DDR3 1600 (PC12800)
2each - PNY 9800GTX+ in SLI mode
Antec NineHundred Two case (all black hell yeah)

Hopefully this should all work together (everytime I buy a new setup usually there is one part that is either DOA or just as likely I selected something incompatible with the rest of the bunch). So we'll see how it goes.


Look forward to seeing you out there in the gaming realms on the new beast.
a b B Homebuilt system
July 26, 2010 5:28:33 PM

Nah, chance's are 50/50, you get a good one, or you get a faulty one,
Life can be harsh :p 
Go for a decent brand named psu, minimise the chances of getting a dodgy one
Good luck man
Moto
!