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Home build won't boot

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March 28, 2010 1:28:06 PM

Hello all, I have a homebuild and recently have been experiencing boot problems. In diagnosing the problem, I've gotten to a choke point for me. If I unplug the 4pin power connector to the MB, all the peripherals work, but the system won't boot. When I plug in the 4pin power connector, the system begins to power for about 3 seconds, then shuts down. Is it the MB, CPU or PS that's the problem here? I don't know if you need further information. Thanks.

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a b à CPUs
March 28, 2010 1:50:38 PM

A list of your full system specs would help :)  This is a very good guide on troubleshooting issues at boot-time. Go through each and every step and double check everything. It's often the case that you think you have done something ok but have just missed something that you only notice when you double check.

Post back after you have tried these and we'll go from there. Good luck :) 
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March 28, 2010 8:41:14 PM

So here's where I'm at:

ZOTAC GF8100-C-E AM2+/AM2 NVIDIA GeForce 8100 Micro ATX AMD Motherboard
AMD Phenom X4 9600 Black CPU
TurboLink Model ATX-CW500P4 500w ATX Power Supply

On a bench test, I have the PS 24pin and 4pin attached to the MB and the HSF and case fan plugged in. Turn on the power, both fans start up and run no problem. Put in the CPU, turn on the power and the fans begin to start up, then shut down immediately. Leave the cpu in and unplug the 4pin, fans run fine. Plug the 4pin back in, fans won't stay running again.

Fried CPU?
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a c 172 à CPUs
March 28, 2010 8:55:45 PM

Full specs include brand and model of everything.

What kind of PSU and motherboard?

Your problem is probably the PSU, or possibly the motherboard.

Work through the "boot problem" sticky.

Then to sort of check the PSU:
Try to borrow a known good PSU.If you cannot do that, try to borrow a DMM to measure the voltages. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.
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March 28, 2010 10:07:00 PM

Okay, so I did the PS paperclip test and it passed. I'll do a full multimeter troubleshoot next.
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a b à CPUs
March 28, 2010 11:28:30 PM

Probably a short, Read the damn guide and take your time.
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March 29, 2010 6:45:10 PM

Ok, so I did a troubleshoot on the psu and the only questionable reading I got was a -10.92v on the blue wire instead of -12v, so I bought a new psu. Breadboard testing with a new PSU gave me the same results. With only the cpu, hsf and new psu attached, I am still not able to get more than a short burst of fan unless I either remove the 4pin power connector or remove the cpu from the motherboard. I don't want to buy a new cpu and motheboard, but I guess I need one or the other or both. Anyone want to guess which I should replace next?

ZOTAC GF8100-C-E AM2+/AM2 NVIDIA GeForce 8100 Micro ATX AMD Motherboard
AMD Phenom X4 9600 Black CPU
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a b à CPUs
March 29, 2010 7:25:25 PM

You may not have your CPU/HSF seated correctly. Without the 4 pin CPU power, the system isn't POSTing. That's why it's not shutting down. With the 4 pin connected, it's trying to initialize your hardware, likely the CPU, and failing.

Do you have a motherboard speaker?
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April 2, 2010 12:14:38 PM

It wasn't a short. It turned out to be the CPU. The 9600 didn't last very long, maybe a year. I put in a Phenom x4 9850 this time. We'll see how it goes.
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a c 133 à CPUs
April 2, 2010 12:17:22 PM

Those first generation Phenoms were bad processors all together so good luck with it I wouldnt expect too much out of it.
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April 2, 2010 12:23:50 PM


At least it was cheap. $80. If I get a year out of this one, I'll be happy. I was afraid of the posts about it running super hot, but so far it's steady at about 40c. I don't know how to change the post header to solved. A little help with that?
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a b à CPUs
April 2, 2010 1:41:02 PM

It will switch to 'solved' if you choose a best answer.
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