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PC Starts/Stops Continously (psu,fans) MB Light is green.

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December 26, 2010 7:01:38 PM

Hello, i bought a new case and i decided to move my system from what case to the other. I am getting the following problem


I have taken the motherboard out of the case to troublshoot.

#1 PSU works fine, i shorted the green/black pin + a case fan and the thing runs fine.
2. the motherboard is out of the system now and onto a piece of cardboard.

Connected is the proper connectors from the PSU, The computer turns on for 1 second both PSU and CPU cooler fan pops on for a split second and then shuts off about 3 seconds later, it does it again, motherboard light is green.


Things i've tried
1 stick of ram
fan off the cpu and the cpu never gets warm during these continual start and stop routine of the fans/psu
CPU out off the motherboard, same problem happens whether CPU is on the board or not.
disconnected fan from the motherboard.... same thing, psu flips on and then off continously.

I have tested the psu by shorting as i said earlier and it stays on fine and runs the case fan fine. Ths PSU is the FATAL1TY 550w...

The CPU is a i3
During these tests nothing is connected to the PSU but the mb connectors and the fan from the cpu...
This is the p7 h55 m pro micro asus board.
December 26, 2010 7:12:10 PM

I just also tried the screwdriver to the 2 pins to see if it was the connector for power button... its not and ive used 2 different cases before this to test today anyway. So i just wanted to be sure, and yeah no work...
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a c 104 B Homebuilt system
a c 887 à CPUs
a c 1153 V Motherboard
December 26, 2010 8:30:57 PM

What about the CPU power connector?
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December 26, 2010 8:55:21 PM

What do you mean?
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December 26, 2010 9:18:02 PM

Both are connected to the motherboard from the PSU , Sorry wasn't more clear. The big one and the smaller one, both are.
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a c 104 B Homebuilt system
a c 887 à CPUs
a c 1153 V Motherboard
December 26, 2010 9:24:06 PM

If that is the case then most likely there something wrong with the board. Have you tried resetting Bios to defaults just in case some setting vent off!
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December 26, 2010 9:33:48 PM

I have removed the battery... I can't get into bios, the computer starts up for a split second and then goes off for 3 seconds, and then it repeats it all over again. I posted over on the asus forum, i am thinking its the motherboard at this point, i inspected all the capacitors and didnt see anything that look like it had been damaged or blown *sigh*
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a c 104 B Homebuilt system
a c 887 à CPUs
a c 1153 V Motherboard
December 26, 2010 9:36:40 PM

Well removing the battery should have reset BIOS so I believe that it is a bad board.
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December 26, 2010 9:49:04 PM

Is it difficult to get asus to swap out mb's? I bought it off newegg in february... i may just plop the $100 on a new one. But, i dunno yet... i wanted my gaming rig to be up in this new case :( 
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a c 104 B Homebuilt system
a c 887 à CPUs
a c 1153 V Motherboard
December 26, 2010 10:01:40 PM

It will take time for them to replace it.
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a b B Homebuilt system
a b à CPUs
a b V Motherboard
December 26, 2010 10:02:16 PM

Do you have a speaker connected to the motherboard? You should be getting beep codes to give you an idea of what's failing.
This computer was working in the other case and just started when you moved it? What about the video card? Maybe it has come off the pci-e slot and is not seated properly anymore. If you follow the link for troubleshooting under my banner it will take you through most of the know issues for this kind of problem. Some won't concern you but try/check most of them it should help. If not give us a more complete parts setup so we can look at it a little closer ourselves.
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December 26, 2010 10:24:26 PM

I took it back out of the case and did all the individual tests on a piece of cardboard to make sure everything worked properly... No speaker codes are coming out at anytime.... and yes that was hooked up for testing too sometimes...
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December 26, 2010 10:59:23 PM

ok i had a very similar problem and i ended up buying a new motherboard when i didn't really have too (although the bad cmos would have eventually drove me nuts anyways).

check your monitors cable. mine went bad in the 30 mins or so my pc was off to run to the store and get a new battery for the cmos.

also if you have a wireless networking card, take that out of your system as well and see what happens.

(i had the both happen to me recently on two different pc's but the wireless card did result in an error beep but the bad monitor cable did not).

both caused the exact same thing to happen. turn the power on and all i would get was the power, fans and such turning on for a brief second, the no signal on the monitor would vanish, then everything would shut off and the no signal would reappear on the monitor, then power would restart and off and the cycle would endlessly repeat.
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December 27, 2010 2:10:38 AM

Nothing is connected except the 2 cables from PSU to motherboard and the CPU'S Heatsink fan, and the power switch cable. NOTHING ELSE. And it does the turns on for a brief second BS... I appreciate your recommendations, i don't know what else to try. I will try to RMA this with ASUS i suppose, but what i am worried about is buying another of the same motherboard and this happening immediately again, i would love to know what is making it do it, did i use the wrong screws to attach the MB to the case? I dunno, this scout case has so many different screws that who knows what works with what.

I've tried everything i could possibly think of, but no matter what the bottom line is, the PSU works when i short it, but when it's attached to the MB it does the split second on/off thing as well with the fans. I have removed the cmos battery, would replacing that battery help at all? I mean this thing is less than 8 months old, and no errors ever before with the date/time etc... I did have a voltage error a long time ago on my old case when the USB port was screwed up (kid spun chair around and broke the USB wireless dongle in the front port, which is the only reason i decided to buy a new case. As my last one worked great. And that happened months ago and it's worked perfectly since i removed the power to the front USB in that case
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