GTX1070 VRM keeps shorting out

[Caspar]

Hi all, I have a GTX1070 that stopped working all of a sudden. My PC lost power all of a sudden and would not power back on unless I remove the 1070 from the machine.

I did some digging and I found the bottom VRM (4C85N) to be shorted on the top FET. The bottom FET appears to be ok. I replaced the VRM but as soon as I power on my PC the VRM gets shorted out instantly. I have tried replacing it twice but I get the same result each time. I don't have enough know how to troubleshoot this and am looking for input to try and figure what the cause is. The card will boot/power on with the VRM/phase removed. See attached picture of the VRM in question.

The next step I thought of trying was to replace the driver but the marking on the chip "02=3C147" can't be found when googling.

Thanks in advance.

[R_J]

Re: GTX1070 VRM keeps shorting out

The ic is likely a RT9611AGQW There could be gate drive resistos that are open but usually if the fet shorts (drain to gate) the ic will be damaged.

[Caspar]

Re: GTX1070 VRM keeps shorting out

The ic is likely a RT9611AGQW There could be gate drive resistos that are open but usually if the fet shorts (drain to gate) the ic will be damaged.

Many thanks for your input. You were right, I found what appears to be an open 1ohm resistor on the back side of the PCB. I am not sure if it's the gate drive or current sensing resistor but the card will stay on with the resistor and 4C85N replaced. May I ask if there's a way to test if the driver is damaged? It's going to take a while for the order of the RT9611AGQW to get here from aliexpress. I looked up the data sheet for the RT9611AGQW and it appears you are also correct on the IC as well. Again, thank you for your very informative input.