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Computer turning off and on, no post help!?

Last response: in CPUs
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September 13, 2013 4:34:04 PM

Hi guys, I have a problem. After installing a new (so I was told but I think refurbished is the term) motherboard, whenever I power it up from the PSU it turns on by itself but the cpu fan doesn't spin and within 1-3 seconds it shuts off. About the same amount of time later it starts again, repeating this cycle endlessly until I cut the power from the PSU. The fan only spins when I remove the 4pin connector for the CPU power than it stays on but I get no post/ my screen stays blank (on or off) and the fan keeps spinning very fast as if under high load. I tried changing Ram sticks, checking the cables, etc. but nothing is working.

I'm thinking it might be that I don't have the original stock cooler and the motherboard area where you screw in the fan has screw holders sticking out slightly making one of my heat sinks useless as it doesn't even touch the surface of the CPU after being screwed in all the way.

I guess my question is whether the heat sink has to apply ample amount of pressure on the cpu in order for it to work? Or is it a faulty Mobo? I've tried everything and have been browsing these forums for sometime trying to find a solution but have had no such luck. Need help please!

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a c 89 à CPUs
a b B Homebuilt system
September 13, 2013 4:45:05 PM

cooler need to apply even pressure to the mounting pint or it can warp the board causing the board to not work or even kill the board.

First thing is you should try to properly mount the cooler then if the issue remains move on to the motherboard being faulty.
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September 13, 2013 4:53:35 PM

Thats the thing, i managed to keep some pressure on the cpu with a different cooler I had except how does that explain it only running when I remove the 4pin power supply and the constant on and off loop its doing?

Sorry if this is not a reply I am on mobile and its confusing me a bit :/ 
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a c 89 à CPUs
a b B Homebuilt system
September 13, 2013 5:03:04 PM

because the uneven pressure on the board from the cooler can warp the PCB and break connection. with the 4 pin connected it could cause a short making the board restart. unplugged it would stop the short.

this is just speculation though. you need to seat the cooler properly then do a diagnosis.

Its like saying the engine in a car spits and sputters but when you bring it to the mechanic it doesn't have a radiator in it so he cant start it to find out.
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September 13, 2013 5:13:24 PM

Ok well I will keep trying to see if I can figure it out as I have been doing for the last 8 or so hours haha

That said I appreciate you trying to help me out. It really amazes me there are still people out there willing to help out a total stranger such as myself. I guess thats why I resort to posting on forums as a last resort. So as to not take advantage. Still I appreciate the help and hope that sometime in the future I can contribute just the same, Again thank you :) 
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September 13, 2013 5:36:23 PM

Update!

Somehow by leaving the old heatsink on with a completely seperate fan, the fan manages to turn on for about 1-2 secs and then it shuts back off.

Strange I was just using the one that doesnt run with the cpu power supply on (but does off) on my other computer and it worked just fine.

Still having the same problem as far as shutting right back off goes. Even when managing to even the pressure from the heatsink and the cpu...
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September 13, 2013 6:07:04 PM

Another Update!!

It turns out after closer inspection of the motherboard that the 4pin connector (that is close to my cpu) sais pwr2 on it!

Does this mean its not a cpu power connector afterall? This is an old board (lga775) and none of my previous ones even had a separate cpu power supply port. So i'm assuming maybe this one doesn't either if that were the case.

If true I suppose it could be the solder on the internal gpu dislodged from excess heat exactly what happened to my last one. Still I did try the external gpu with the same result. Assuming this were all true than this board doesn't auto-detect my external gpu it seems and without booting into the Bios might be just as useless...

Don't mind my ramblings if you read this. I suppose you can say this thread is a journal of sorts where I might track my progress in the attempt of forming together any cohesive thoughts. Either that or preserving what little is left of my sanity so that I might backtrack should I find myself lost. Iow the ramblings of a mad man, pay it no mind :) 
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September 13, 2013 6:22:22 PM

Yet another update!!!

I just discovered how important standoffs are! I didn't think they were and seeing as this one didn't come with any I thought it was no big deal leaving them off. Boy was I wrong... Or so i think... still need to read up some more as to why this is so but its been reported to be a cause of a number of booting issues so I'm going in, wish me luck!!! You watchful Guardian you :) 
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September 13, 2013 6:46:47 PM

Hmmmm.... I must bear with myself, I am doing my research on a mobile which is a bit difficult. Nevertheless I did manage to salvage a few (2) standoffs from the old motherboard I demolished with a hammer outside of a broken home several days ago in complete darkness, which is quite an accomplishment in and of itself. That having been said, So long as there is progress I must push forward! If only for your sake; Mother........board.........

~The Strange Stranger~

(Update) thus upon unscrewing the motherboard he gazed in horror as he realized that his so called standoffs were not but plastic versions with no wholes to be seen. Only glue... Lots of glue! O.o' bewildered with this sudden realization he decided to do a google image search and as fate would have it, his fate was sealed just as the standoffs that lay before him.
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September 13, 2013 7:38:18 PM

Chapter VI - The Final Stand

With the realization that it had all been for not. The young man thought he'd indulge in one last desperate attempt. He figured that as with most stories, he too had earned a happy ending to his own and thus having managed to create what he would then call a breadboard, he succeeded(obviously). But all did not go as planned... That is of course unless you planned for failure in which case was precisely what he did! "So does this mean!!!!!!!!!!!!!!!? Unfortunately not, he got what he had planned thus in turn sacrificing his Mother for Bread... A breadboard mind you.

Although I do suspect this story is far from over, tonight the young man was feeling rather hungry and so he ate said bread and retired for the night.

~To be continued.....~
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a c 89 à CPUs
a b B Homebuilt system
September 13, 2013 9:05:13 PM

OK the reason the standoffs are important is they keep the soldered joints from touching the metal motherboard backing plate. Like with any electrical part if it touches metal it will short out.

Motherboards do not come with standoffs. These are supplied with the case. When you purchase a new case, they will supply the standoffs in the parts bag.

I do not recommend gluing standoffs to the backing plate. Most cases have screw holes for the brass standoffs to screw into.

If you do not have standoffs between the board and back plate you take the chance of frying the board and/or CPU. If you don't have the standoffs (If I read your posts correctly, you don't) give this method a try. Take everything out of the case and do a bench build. This is just a temp trial to see if the issue is the standoff/case issue. Build it out of the case on the wooden table/desk and try and see if it will boot. If it does you can purchase standoffs and screws if need from an online PC outlet. To turn the power on you can use a small screwdriver to touch the 2 front panel power pins together.

If it does not boot then the issue will most likely be the mother board is bad.

Your 4 Pin power connector. This is normal to have these now to help supply the CPU and other components with enough power. all LGA775 sockets had this connector and every desktop motherboard since has them. It does need to be plugged in for the PC to operate correctly. It is a supplemental power source for the CPU and motherboard.
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September 13, 2013 9:22:06 PM

Ha! yeah sorry I noticed that my other build does infact have a 4pin cpu power connector, but is it required to operate if at least for several minutes? Because it only shuts off when I plug it in otherwise it continues to run but still I get no boot screen/blank screen. So I really don't know what to make of that.

Also I did try laying it on a board, I thought thats what breadboard meant? Lol still that didnt seem to work either so I'm thinking of just shipping this one back and having it replaced. I just really didn't want to resort to that because of the time it'll take to arrive. Suppose I have no choice though it must be bad... Still thanks again for trying :) 
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a c 89 à CPUs
a b B Homebuilt system
September 13, 2013 9:29:36 PM

yes the four pin connector is necessary for the PC to boot properly.
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September 13, 2013 10:56:51 PM

Wow it turns out both the cpu's I tried it with were damaged, stranged considering one was just working up until recently and the other I just purchased(used) specifically for this build. Iow I got ripped of for the cpu -_-'

In anycase I got it working after trying a third and final cpu after re-unpacking the motherboard that i just got ready to ship out... Figured I'd give it one final shot and it worked! Thanks again bgunner! XD
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a c 89 à CPUs
a b B Homebuilt system
September 14, 2013 5:16:25 PM

the odds of having 2 bad CPU's are high but not unheard of. I'm glad you were able to figure out the issue. Most people don't have access to 3 different Socket 775 CPU's.
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