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Motherboard killer?

Last response: in Motherboards
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October 15, 2010 6:02:51 PM

Hello,
System appeared to have a dead motherboard. Replaced it and everything appeared fine for about ten minutes then the system went down.

Now no video again.

Old board: cpu fan spins, drives power up, no beep codes unless memory is removed

New board: cpu fan does not spin, drives power up, no beep codes unless memory is removed

Followed the steps in PERFORM THESE STEPS before posting about boot/no video problems!. Replaced power supply, memory, cpu on both boards, all to no avail. Both have onboard video.

Could the old power supply have killed both boards?

More about : motherboard killer

October 15, 2010 6:26:20 PM

It's possible. You can buy a PSU tester for about 10 bucks I think. It's a really good investment. You can test your rails to see if any are over volting. Good Luck.
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October 15, 2010 7:08:21 PM

Testing with a multimeter (using paperclip with only a case fan connected) yielded the following:
Yellow wire +12 volts.
Red wires: +5.2 volts
Orange wires: +3.3 volts
Blue wire : -11.1 volts
Violet wire: 5 volts
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October 16, 2010 12:28:42 AM

Actually, I think that looks decent. as long as that 5v isn't any higher than 5.6, 5.2 is fine? maybe contact the board manufacturer and see what they say?
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October 16, 2010 3:02:30 AM

Yes, the voltages are all within tolerances. Very strange. Been through the support forums for both boards but couldn't find any answers.
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October 16, 2010 3:54:26 AM

does your board (s) have on board video?
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a c 156 V Motherboard
a c 172 à CPUs
a b } Memory
October 16, 2010 4:19:11 AM

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 beep 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.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case.

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

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

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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a c 716 V Motherboard
a b à CPUs
a c 347 } Memory
October 16, 2010 4:40:52 AM

ever7 said:
Could the old power supply have killed both boards?

Possible sure, that would suck!

Before throwing in the towel, I would either breadboard the MOBO {physically removing the MOBO and placing on cardboard & wiring it to PSU, HDD, etc running it outside the case}, or easier method remove ALL mounting screws and dangling on a towel inside the case. In other words, determine if there is an electrical SHORT.
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a b V Motherboard
a b à CPUs
a b } Memory
October 16, 2010 5:06:51 AM

Jaquith has the right idea.

I'd guess I'd have a hard time trying to use that psu again until its conclusively eliminated as the source of the problem, ie, getting this board to run with it. A psu tester or a multimeter just cannot detect all the ways that a psu can be troubled, and cause trouble.
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October 16, 2010 1:07:36 PM

Ahumphers91: both boards do have onboard video

jsc : I did work through the guide (twice actually) and yes, it is excellent but didn't help sort out this particular problem unfortunately

jaquith: breadboarded both motherboards using a known good psu, new cpu, new memory

I appreciate the input because I'm really stuck on this one
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a c 716 V Motherboard
a b à CPUs
a c 347 } Memory
October 16, 2010 4:16:49 PM

If "both" boards are using the "same" CPU then your CPU maybe the problem. Please clarify.
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October 16, 2010 6:14:11 PM

jaquith said:
If "both" boards are using the "same" CPU then your CPU maybe the problem. Please clarify.


Have replaced both cpu and memory as noted above
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a c 716 V Motherboard
a b à CPUs
a c 347 } Memory
October 16, 2010 8:38:20 PM

^ How about the Keyboard & Mouse?
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October 16, 2010 8:48:46 PM

jaquith said:
^ How about the Keyboard & Mouse?

running without for now as I just want it to POST or at least show me something on the monitor (which is a known good monitor)
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a c 716 V Motherboard
a b à CPUs
a c 347 } Memory
October 16, 2010 9:36:08 PM

If I brought in (2) good PCs that worked and suddenly neither works then I look at ALL common elements:
Monitor
Keyboard
Mouse
Any Devices
Even the wall socket including the power strip
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a b V Motherboard
a b à CPUs
a b } Memory
October 17, 2010 12:04:09 AM

. . . and I believe the most suspicious common element is the psu.
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October 17, 2010 3:20:26 AM

jaquith said:
If I brought in (2) good PCs that worked and suddenly neither works then I look at ALL common elements:
Monitor
Keyboard
Mouse
Any Devices
Even the wall socket including the power strip


None of these are common: there are no devices connected other than a known good monitor
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October 17, 2010 3:21:22 AM

Twoboxer said:
. . . and I believe the most suspicious common element is the psu.


I reiterate: am now testing with a known good psu
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a b V Motherboard
a b à CPUs
a b } Memory
October 17, 2010 4:14:00 AM

Sorry, Ever, but nowhere could I find you saying that.
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Best solution

a c 716 V Motherboard
a b à CPUs
a c 347 } Memory
October 17, 2010 7:21:08 PM

Then it seems pretty clear that the PSU killed both MOBOs. I've had a bad PSU kill (2) GPUs on (2) PCs; the PSU was Antec - years ago and I learned a thing or two about PSUs since. The PSU must have 1 rail and must use Japanese capacitors.

Good video - http://www.youtube.com/user/3DGAMEMAN#p/search/1/gN2ja-...

Good Luck!
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October 24, 2010 1:01:25 PM

Best answer selected by ever7.
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