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Help!!! Did I Fry My Motherboard????

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November 25, 2010 9:17:06 PM

Ok, so here's the deal....

I was installing a new HS last night onto my processor, got everything on there good, no problems, etc got everything back in place...

Then when I went to turn on the computer, it wouldn't stay on.. the fans came on for about a second, then it'd shut off... did this about 3 times... and then wouldn't come on at all.. nothing..

WELL I looked and it turns out that I forgot to plug-in the CPU power...

So, I plug it in and then of course nothing will come on... the motherboard green light will come on, but nothing will turn on. no fans, no nothing...

The PSU works still just fine as I plugged it into this computer and it turned this one on just fine...

So am I right in thinking I probably fried my motherboard? or could it be something else?

Everything is connected right, and it all was working 100% before... I even went as to try and make sure I didn't use too much thermal pasts, etc.. all seemed ok though.

Thoughts here?

I am going to order a new motherboard tomorrow probably if that is it, but I want to be sure it's not something else... would hate to spend $$ on a mobo and that not be it..

Thanks in advance!!

More about : fry motherboard

November 25, 2010 11:44:50 PM

Try to clear your CMOS:

There should be a jumper on your motherboard.

1) Power down.
2) Move the jumper. Leave it there for 5 seconds
3) Move the jumper back to default position.
4) Power up again.
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November 26, 2010 1:05:04 AM

julioshingon said:
Try to clear your CMOS:

There should be a jumper on your motherboard.

1) Power down.
2) Move the jumper. Leave it there for 5 seconds
3) Move the jumper back to default position.
4) Power up again.


Yeah, I tried doing that... I wish it were that simple.

It's just as if it won't turn on at all.... Nothing comes on except the green motherboard light.... no fans, no nothing.... I even thought maybe the case jumper was being buggy so used the power jumper from another case, but that didn't work either.... at a total loss :/ 
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November 26, 2010 3:09:36 AM

just a thought , you might try to re-install your old HS,check the paste on both the new and old.
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November 26, 2010 3:12:06 AM

discboy321 said:
just a thought , you might try to re-install your old HS,check the paste on both the new and old.


yep, did that too lol....

It's really damn weird...

Who knew leaving off that 4-pin connector and trying to start it up would cause so much havoc?? :ouch: 
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a c 122 B Homebuilt system
a c 156 V Motherboard
November 26, 2010 3:14:53 AM

OK. Time for some serious, systematic troubleshooting:

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beeps patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:
http://www.cwc-group.com/casp.html

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU.

Motherboard LED's mean very little. When on, all they are telling you is that the computer os plugged into a live power socket and the PSU is switched.

Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. 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. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

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.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card. Silence or long single beeps indicate a problem with the memory.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
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November 26, 2010 3:48:06 AM

jsc said:
OK. Time for some serious, systematic troubleshooting:

Work through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beeps patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:
http://www.cwc-group.com/casp.html

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU.

Motherboard LED's mean very little. When on, all they are telling you is that the computer os plugged into a live power socket and the PSU is switched.

Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. 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. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

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.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card. Silence or long single beeps indicate a problem with the memory.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.


Thanks for that.... About the only thing I didn't check in all of that was that one test for the PSU there you showed... Just did that and then PSU worked like a charm with that trick. My PSU even has a turbo fan that I was able to turn on with no problems....

It's as if for some reason, the motherboard shorted and can't send that signal to the PSU... It's really damn weird and frustrating.
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a b B Homebuilt system
a c 171 V Motherboard
November 26, 2010 9:12:05 AM

There have been any number of threads where people have forgotten to plug in the 4-pin CPU connector. Plug it in and the system fires right up. I find it hard to believe (though not entirely out of the question) that you not having it plugged in fried the board.

Just a few days ago, I rebuilt my HTPC and ran into the same problem as you: fire it up, fans spin for a second, then nothing. For me, it turned out one of my front header cables was incorrectly connected. I know you said everything was connected correctly. I'd recheck it, thoroughly, one more time.

In fact, I'd probably disconnect all chassis to motherboard connections (front USB Headers, chassis fans, HDD and activity light, and probably even the reset switch). Of course, I'd probably go with just the bare minimum of components installed as well. If it fires up at that point, then start adding the connections back one at a time to see where it's failing.

-Wolf sends
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November 26, 2010 5:28:10 PM

Wolfshadw said:
There have been any number of threads where people have forgotten to plug in the 4-pin CPU connector. Plug it in and the system fires right up. I find it hard to believe (though not entirely out of the question) that you not having it plugged in fried the board.

Just a few days ago, I rebuilt my HTPC and ran into the same problem as you: fire it up, fans spin for a second, then nothing. For me, it turned out one of my front header cables was incorrectly connected. I know you said everything was connected correctly. I'd recheck it, thoroughly, one more time.

In fact, I'd probably disconnect all chassis to motherboard connections (front USB Headers, chassis fans, HDD and activity light, and probably even the reset switch). Of course, I'd probably go with just the bare minimum of components installed as well. If it fires up at that point, then start adding the connections back one at a time to see where it's failing.

-Wolf sends


Yeah, disconnected everything I could.....

I even hooked up the power connectors from another case just to see if that could get it to start (in case it was my case power) and nothing... No beeps, no nothing....
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December 2, 2010 2:40:33 AM

So it does look like after all, that I did fry it. Something went terribly wrong.

I bought a new motherboard and it hooked right up with everything just fine. Powered up instantly. So my guess is leaving that 12v rail caused it to pull too much power maybe? Really I have no idea... just glad to have my system back, that's for sure!
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