Hi all,
I have a 3080 with seemingly correct rail resistances and all voltages present apart from the PEX,
12VEXT: >1KOhm and rising: 12v
5V: 2.4KOhm: 5v
1.8V: 2.3KOhm: 1.8v
MEM 54Ohm: 1.3v
PEX: 5.1Ohm: 0v
I found that a zero ohm resistor that powers the AOZ2261NQI-11 IC (from 12v EXT) which generates PEX was open,
on further inspection the IN rail of the chip was shorted, I injected voltage and saw it warm up, once the chip was removed short was still present and I realized it was coming from the other side of the board because of a shorted capacitor. Once removed the short was gone. Unfortunately on desoldering the IC i cracked it so I'm waiting for a new one to arrive.
In the meantime I tried to feed 0.95v to the PEX from my bench power supply, when the PC is off it draws 56mA of current, once I turn the pc on this jumps to 200mA however still no post or video, as the core heats the PEX resistance drops and current keeps climbing, not sure if this is expected behavior but I limited my bench to 700mA to avoid damaging it.
Any reason why still no video? Maybe something to do with the PGOOD signal? But it seems like it's pulled up via a resistor so should be present even without the chip.
On a side note, although probably unrelated, I also found a melted capacitor close to the PCIE connector on the back of the card which was melted open, between the 12v EXT and GND. But I suspect this was a prior incident that didn't kill the card.
Thanks In advance!
I have a 3080 with seemingly correct rail resistances and all voltages present apart from the PEX,
12VEXT: >1KOhm and rising: 12v
5V: 2.4KOhm: 5v
1.8V: 2.3KOhm: 1.8v
MEM 54Ohm: 1.3v
PEX: 5.1Ohm: 0v
I found that a zero ohm resistor that powers the AOZ2261NQI-11 IC (from 12v EXT) which generates PEX was open,
on further inspection the IN rail of the chip was shorted, I injected voltage and saw it warm up, once the chip was removed short was still present and I realized it was coming from the other side of the board because of a shorted capacitor. Once removed the short was gone. Unfortunately on desoldering the IC i cracked it so I'm waiting for a new one to arrive.
In the meantime I tried to feed 0.95v to the PEX from my bench power supply, when the PC is off it draws 56mA of current, once I turn the pc on this jumps to 200mA however still no post or video, as the core heats the PEX resistance drops and current keeps climbing, not sure if this is expected behavior but I limited my bench to 700mA to avoid damaging it.
Any reason why still no video? Maybe something to do with the PGOOD signal? But it seems like it's pulled up via a resistor so should be present even without the chip.
On a side note, although probably unrelated, I also found a melted capacitor close to the PCIE connector on the back of the card which was melted open, between the 12v EXT and GND. But I suspect this was a prior incident that didn't kill the card.
Thanks In advance!
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