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Motherboard Shorting HD

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August 9, 2010 9:03:46 PM

Hi Everyone,

I have been trying to build a new comp and ran into an issue with the motherboard shorting out the hd. I sent the motherboard back to Gigabyte and they replaced the bios chip and said it successfully completed their tests. My question is: Would replacing the bios chip stop my hard drive from shorting out? I would really appreciate it if someone could help me out. I really want to finish this computer.

GIGABYTE GA-EP45-UD3P LGA 775 Intel P45 ATX Intel Rev. 1.6

Intel Core 2 Quad Q9550 Yorkfield 2.83GHz LGA 775 95W

CORSAIR CMPSU-650TX 650W ATX12V

SAPPHIRE 100283L Radeon HD 5770 (Juniper XT) 1GB 128-bit

Western Digital Caviar Black WD1001FALS 1TB

CORSAIR DOMINATOR 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500)

HP 24X Multiformat DVD Burner Black SATA Model 1270i

Linksys WMP54GS 32-bit PCI Interface Wireless-G Adapter

More about : motherboard shorting

a c 177 V Motherboard
August 9, 2010 9:32:11 PM

First step toward an explanation would be to define, exactly, what you mean by "shorting out" the HD?
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a c 97 V Motherboard
August 9, 2010 10:18:28 PM

Agreed. I have no idea how a Mobo would cause that.

My uncle who works for "the post office, you know. The one in DC" tells me the story of a tech who came to him for help. It seems this tech had replaced the drive 3 times over the span of about a year. He wanted to know how that could be. My uncle suggested checking the PSU, and they found the +5V rail was outputting ~7V. This was frying the motor in the drive, and causing the many replacings. This time they replaced the drive and the PSU, and now works fine. I see this being much more possible then a bad mobo.
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August 10, 2010 1:07:32 AM

bilbat said:
First step toward an explanation would be to define, exactly, what you mean by "shorting out" the HD?


What i meant by shorting out was that when i plugged the hard drive in smoke started to come from it and then it shut off and would not turn back on. Thank you for your help.
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August 10, 2010 1:12:45 AM

4745454b said:
Agreed. I have no idea how a Mobo would cause that.

My uncle who works for "the post office, you know. The one in DC" tells me the story of a tech who came to him for help. It seems this tech had replaced the drive 3 times over the span of about a year. He wanted to know how that could be. My uncle suggested checking the PSU, and they found the +5V rail was outputting ~7V. This was frying the motor in the drive, and causing the many replacings. This time they replaced the drive and the PSU, and now works fine. I see this being much more possible then a bad mobo.


How would I check what each rail is outputting? With a voltmeter? Thanks for your help.
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a c 177 V Motherboard
August 10, 2010 3:40:24 AM

Quote:
What i meant by shorting out was that when i plugged the hard drive in smoke started to come from it and then it shut off and would not turn back on.

Holy crap!! :o 

That's 'shorted' all right!

Let's get the sequence here... You assembled it with the main power off, correct? You say 'when you plugged it in', but I'm assuming this happened after you plugged it in, when you turned it on? My guess would be that one of your plugs got blackened by the incident - which one was it, the narrow one (the data plug), or the wide one (the power connector)? Is it at all possible that, somehow, a piece of debris got lodged inside one of the connectors?

I'm trying to guess what this could possibly have to do with your BIOS ROM, and can't even begin to formulate anything!

As far as the power supply goes, there are some simple checks you can perform. If you look at the last item in the GB 'sticky', the Power Supply - Basic section, it gives pointers to two things - the 'paper-clip trick', which can be used (carefully!) to short a pair of pins to turn on the supply, and the connector pinout, which will show you which pins to check for what voltages - and, even unloaded, all the voltages should be within, say, 5% of nominal...
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a b V Motherboard
August 11, 2010 1:08:25 AM

The first thing to do is to check out the function of the PSU separately.

The most direct way to check the voltages is with a digital voltmeter. On the 24 pin power connector, you can short out pins #16 (pwr on) & #17 (gnd) to turn on the PSU. Then you need to check the 5 volt (red) rail, the 12 volt (yellow) rail, and the 3.3 volt rail (orange) to see the voltages match. This is technically finniky.

Several years ago I picked up a $15 PSU checker on the net, which you plug the 20 or 24 pin power connector in, the molex 4 pin power connector, the PCI-e connector, a SATA power connector. and the 12VATX DC connector. LED's on the small unit tell you if the voltages are correct. It has been a very handy tool several times. You might acquire or borrow one as a safe way to check the PSU without plugging anything into it.

If you know the PSU is good, you could plug in the MB 24 pin power connector, and the 12 V CPU either 4 pin or 8 pin ATX connector. Without connecting any hard drive, power cord splitter, or other device, POST the MB to the System SetUp screen, & on the PC Health screen the voltages, temperatures, and fan speeds are listed. You could then check the peripheral Molex, & SATA connectors for correct voltages.

Don't think you mentioned what kind of HDD you are referred to, but if a PATA, a 4 pin molex connector could have been "forced in" backwards placing 12 volts on the 5 volt HDD pin. It's not too hard to do since most take some force to push on correctly. The molex connector has 12 volts on the yellow wire, pin 1, on the most right side of the HDD looking at it from the pin connector view.

If a SATA drive, could a molex to SATA power connector been used and the 2 molex connectors been connected backwards? Because of the keying, a 15 pin SATA power connecter can't be pushed into a SATA power slot.
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August 15, 2010 3:55:54 AM

I got a digital power supply tester that shows the exact voltage. All the connectors fell within in the correct range. The hard drive is SATA. Thank You for your help John.
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August 15, 2010 4:03:37 AM

bilbat said:
Quote:
What i meant by shorting out was that when i plugged the hard drive in smoke started to come from it and then it shut off and would not turn back on.

Holy crap!! :o 

That's 'shorted' all right!

Let's get the sequence here... You assembled it with the main power off, correct? You say 'when you plugged it in', but I'm assuming this happened after you plugged it in, when you turned it on? My guess would be that one of your plugs got blackened by the incident - which one was it, the narrow one (the data plug), or the wide one (the power connector)? Is it at all possible that, somehow, a piece of debris got lodged inside one of the connectors?

I'm trying to guess what this could possibly have to do with your BIOS ROM, and can't even begin to formulate anything!

As far as the power supply goes, there are some simple checks you can perform. If you look at the last item in the GB 'sticky', the Power Supply - Basic section, it gives pointers to two things - the 'paper-clip trick', which can be used (carefully!) to short a pair of pins to turn on the supply, and the connector pinout, which will show you which pins to check for what voltages - and, even unloaded, all the voltages should be within, say, 5% of nominal...




Yes you are right i meant when i turned the power supply on. I got a digital power supply tester and the voltages all are within the proper range for each connection. I can't tell which cable got blackened the ends are the color of black and I can't visually see if anyone of them are any darker sorry. Thank you for your help bilbat
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a b V Motherboard
August 15, 2010 5:38:01 PM

Hi Kidspin,

Lets review, you checked the PSU with a power supply checker and the voltages are correct. That means the PSU is working.
The next step would be to connect the PSU to your Motherboard, 24 pin power connector, either 4 pin or 8 pin 12v ATX accessory power near the CPU, with your graphics card, and keyboard, but No HDD or DVD or Floppy or any other peripherals connected.

Turn on the power switch on the MB and it should POSt. In the System Setup check the PC Health section to see that the voltages on the 12 V, 5 V and 3.3 V rails are OK.

If all goes OK, then with the power supply on , use the digital PSU checker if still available, and plug each power molex connector separately into the checker to see that the volages read correctly. Do the same for the SATA power connectors, and if a PCI-E connector is present, check them.

You didn't mention if your PSU has modular power cords, or if hard wired into the PSU. Also it is important to know if you are using a "Molex 4 pin to SATA power conector for the SATA Drives or Sata power connectors directly from the PSU.

If somehow the Molex connector was connected backwards, you would have put 12 V on the 5 V line. The HDD's are wired so that the motor that spins the disc platters is 12 V, and the electronics and chips on board are 5 V. That theoretically could have burnt out the HDD electronics.

The safest way to check the SATA power 15 pin connectors, is to use the digital PSU checker, rather than with a DVM since the 15 pins are very close together and could be shorted with your probe. Each of 3 pins carry (from pins 1 to 15), 3.3v, gnd, 5 v, gnd, & 12 V.

If you were able to see in spec voltages in the System Setup PC Health, you will have to assume the HDD is defective and replace it.
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