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Old 04-10-2012, 04:59 AM   #1
Th3_uN1Qu3
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Question Gigabyte 8IGMIU no POST

Got this board in an IBM Netvista machine for free. Reportedly smoke came out of it. Wouldn't POST or beep. I thought it was the PSU but it proved to be fine - i found a scorched FET near the RAM slots, it was the RAM regulator. It was so bad the drain pad came off with it.

I ghetto'd a 40N03P in there (the kind used for making 3.3v in some cheap PSUs) and i got the no memory beep. Put one stick of RAM in and it fired right up. Put the second one in and it froze, and since then it doesn't want to POST anymore. I still get the no memory beep when no RAM is installed, but when i put RAM in i get nothing. Memory voltage seemed a bit low so i hacked the regulator to deliver more, but still no go. RAM tests fine in another board.

I found a single questionable cap (chipset power supply) and it's been replaced already. I'm out of ideas on this one. I'm not too keen on fixing it, but what i did on the RAM regulator looks so ghetto it'd be fun to actually have this working.
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Old 04-10-2012, 12:26 PM   #2
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Default Re: Gigabyte 8IGMIU no POST

try a different reg
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Old 04-10-2012, 05:42 PM   #3
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Default Re: Gigabyte 8IGMIU no POST

The reg is the MOSFET which i've replaced. It's driven by a TL431. Anyway, it's not the reg nor the RAM, screw it. It's already been chucked into the "for parts" box.

The case on the other hand is pretty nice - it accepts any microATX board and the power supply draws air from the CPU cooler, that's a pretty efficient heat removal mechanism. I'm not yet sure if i'll give it away for $10ish or i'll keep it for my server project... that Dell PIII i got suddenly doesn't seem so attractive anymore, since this puppy can take a board with a better and more power efficient CPU, like say a Pentium Dual Core.
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Old 04-10-2012, 10:12 PM   #4
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Default Re: Gigabyte 8IGMIU no POST

If the board still beeps without RAM, it still might be okay. Perhaps the RAM filter capacitor(s) are bad (and perhaps that's why the original MOSFET blew?). Try a RAM module that has less RAM chips on it. Also, what's the driving voltage on the Gate of the MOSFET and where is it derived from?
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Old 04-11-2012, 03:11 AM   #5
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Default Re: Gigabyte 8IGMIU no POST

Yes it beeps but once i put ram in it's dead. Don't have any ddr smaller than 256. Gate voltage is 4.5ish v, it's driven by a 431 like i said, it's a linear. Caps on the ram are Choyo but i tried others, still no go. I also reflowed the NB only to get the same behavior.

It won't take a Prescott so it's not worth much anyway.
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