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Comp won't POST with either of 2 mobos

Last response: in Motherboards
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October 12, 2010 1:49:34 AM

First of all, I gave up on my EVGA nVIDIA 680i when it had a recurring problem where it wouldn't even start booting Windows (XP SP3) due to an nVIDIA driver error "nvata.sys is missing or corrupt." Tried a full reinstall of Windows multiple times only to have the machine eventually deteriorate after a week or so to the same point, so I replaced it with a Gigabyte EP45-UD3P.

Machine worked decently well for a few weeks, but then I started getting all the same old errors again... "delayed write failed," which would lead to freezes (that oddly enough wouldn't go to blue screen unlike with the EVGA mobo,) and then boot failures that required a CMOS reset to get around. I experienced all of these with the EVGA mobo.

The latest iteration is a failure to POST where the boot cycle runs normally through the "verifying DMI pool data" step after which it tries to boot Windows. The comp then restarts, but now the CPU (Intel E6600) isn't listed in the POST process. It still reaches the same step in the boot process and then restarts, again without recognizing the CPU. CMOS reset does nothing.

Out of curiosity, I reinstalled the old EVGA mobo, which is still in the same shape ("nvata.sys is missing or corrupt") but the POST code on the LED display shows "FF" which is "Boot." This leads me to believe that the EVGA board doesn't notice any problems with the CPU...

I am so utterly stumped by this months-long process of trial and error... please, somebody help. Full hardware configuration below:

Mobo: Gigabyte EP45-UD3P -OR- EVGA nVIDIA 680i
CPU: Intel E6600, not overclocked
RAM: 2x 1GB Corsair DDR2 1066 (PC2 8500)
HD: 2x WD Raptor 150GB, not in RAID
GPU: GeForce 8800 GTS
Removable drives: DVD-RW, DVD-ROM, floppy
OS: Windows XP, SP3

More about : comp post mobos

a b V Motherboard
October 12, 2010 2:27:32 AM

My first thoughts are that you have a faulty power supply; substitution of the power supply would be one of the first things that I would try. If replacing the power supply does not cure the problem then I would run a memory test program such as memtest86 and if this turns up no problems then I would suspect the hard drive.
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a c 1155 V Motherboard
October 12, 2010 2:28:28 AM

Have you scanned the hard drives for errors? Presuming that you do a reinstall (at least repair) of Windows and drivers after swapping motherboards.
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October 12, 2010 2:36:24 AM

Rolli, I have scanned the hard drives with multiple tests and checked their performance against baselines... no errors whatsoever.

pjmelect, I haven't tried replacing the power supply. Is there something I could use to test it before shelling out the cash for a replacement?

Also, a quick update... the EVGA mobo is now in the exact same shape as the Gigabyte one... won't even attempt to boot Windows, even on a buddy's spare hard drive, just cycles back to the POST screen. It does display the CPU every time though.
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a b V Motherboard
October 12, 2010 4:28:14 AM

Substitution is the only reliable test of a power supply. Can’t you try your buddy’s power supply? Failing that take the computer to a friendly computer shop and get them to swap the power supply. If it cures the problem then you will have to buy the replacement from them of course.
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a c 156 V Motherboard
October 12, 2010 4:39:39 AM

My first guess would also be PSU. You have the same problem with two different brands of motherboards.

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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November 20, 2010 9:53:59 PM

jsc said:
My first guess would also be PSU. You have the same problem with two different brands of motherboards.

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.
...


Thanks, jsc. I worked through the whole thread and have some new info. Everything was fine up until I got to breadboarding the mobos, where I got different results with each. The Gigabyte mobo did not even beep when only the CPU and fan were installed. After powering up, the "phase LEDs" would light up and the CPU fan would spin up, but after about 5 seconds the system would restart. I tested the voltages on all the wires in the mobo and CPU power cords while they were under load, and all tested good within the appropriate tolerances EXCEPT for the gray wire, which came in at +4.63V. I noticed that there was no wire in pin 20, which the Gigabyte manual says should have a -5.0V wire in it.

Due to this development, I reinstalled the EVGA mobo out of curiosity. I installed the CPU and fan and, surprisingly, got the appropriate long beep. I tested the voltages under load, and they were all the same except for (you guessed it) the gray wire, which read +5.10V. The wire in pin 16 (listed as "power supply on" in the Gigabyte manual) also tested at a different voltage... 0.0V on both mobos with the power on, but with the power off it read +3.86V on the Gigabyte mobo and +3.47V on the EVGA mobo. The EVGA mobo passed the breadboard test step by step to the point where I had the GPU in and the system POSTing to the point it was at before (continuously restarting immediately after "verifying DMI pool data.")

I can't tell if this means the PSU is fine and the Gigabyte mobo is simply more broken than the EVGA or what. Any ideas?
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a c 156 V Motherboard
November 28, 2010 1:46:09 AM

First, the requirement for -5 volts went away years ago. Because I have both a GA-EP45-UD3P (and a UD3L and P35-DS3P :)  ) and an eVGA 680i I can tell you that none of them need -5 volts.

Next, the grey wire carries the PowerGd signal to the motherboard. This should go to a Logic HIGH - around 5 volts. Anything over 3.5 volts is OK.

The green wire, before you turn on the computer with the case switch off, should be at somewhere around 5 volts. Momentarily pressing it will cause the green PSU line to drop to zero, telling the PSU to turn on.

I think it should go back to 5 volts. Otherwise the PSU cannot detect when it is being pressed for several seconds (the signal to shut down the PSU). I don't know for sure because I am on vacation away from my desktopn systems and all I have is my little netbook.

Does the Gigabyte board have a case (system speaker) installed? The eVGA board has one built in. The Gigabyte board does not.

So if you do not have one plugged into the Gigabyte board, we do not really know what is happening when we try to boot.

Back to the eVGA board. Do you get the single short beep before "DMI fails ..." and the system restarts?

If so, try running memtest86+ to check your memory.

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a b V Motherboard
November 28, 2010 2:21:22 AM

The detecting of the power button for several seconds is performed by the motherboard. To turn on the power supply the green wire must be kept at zero volts (logic zero up to 0.8v).
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November 28, 2010 7:45:57 PM

First, regarding the eVGA board since it's the one I had installed at the time...

jsc said:
Back to the eVGA board. Do you get the single short beep before "DMI fails ..." and the system restarts?

If so, try running memtest86+ to check your memory.


No, there is no sound whatsoever when it restarts until the short beep indicating a good POST. And it doesn't return an error or say there's any failure when it tries to verify the pool data. Couldn't successfully get the computer to boot memtest86+ off of a cd, but I did have a copy of Windows Memory Diagnostic sitting around on a floppy. All 6 of its tests ran 10 times each without finding any errors.

Also, the computer still shuts down normally (with both boards) when the power button is held for 5 seconds, so there's no problem with the voltages there.

Now, for the Gigabyte board...

jsc said:
Does the Gigabyte board have a case (system speaker) installed? The eVGA board has one built in. The Gigabyte board does not.

So if you do not have one plugged into the Gigabyte board, we do not really know what is happening when we try to boot.


I wasn't sure if it had an onboard speaker, since I couldn't find one in the manual's diagram or on the board, but another thread led me to believe it did. Obviously, I was wrong, but my case (Cooler Master 830) doesn't have a speaker to plug into it... I'm working on borrowing one from a friend.

Is there anything else I can try in the meantime with either board?
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