MSI GTX-980ti shorted MOSFET on memory rail

[daemon123]

Hi All,
I have this MSI GTX-980ti Gaming Golden Edition. It had shorted mosfet on memory. Replaced the shorted i.e. Q47 PK616BA with 4C09N and the card ran fine for a month. Then suddenly again the same problem. This time when i replace it 4C09N or with replacement PK616BA (Aliexpress) it gets shorted. As soon as turn on the PC the PSU shuts down and the same mosfet Q47 gets short.
What should be the next step. Kindly guide.
The board view files for this gpu is available and attached. https://www.badcaps.net/forum/showthread.php?p=1237952

[ktmmotocross]

Re: MSI GTX-980ti shorted MOSFET on memory rail

replace mosfet controller

[daemon123]

Re: MSI GTX-980ti shorted MOSFET on memory rail

replace mosfet controller

Thanks for quick response.

That would be U8 ?
The markings on it are hardly readable.

"08 2F
227"

What should i look / search for ?

[ktmmotocross]

Re: MSI GTX-980ti shorted MOSFET on memory rail

schematic
https://www.badcaps.net/forum/showthread.php?p=1237952

[daemon123]

Re: MSI GTX-980ti shorted MOSFET on memory rail

Thanks again ktmmotocross for quick reply.
I am not an expert. Looked through the file and found the relevant section on page 30.

The U8 seems to be either RT8809 or APW8700, looking at the pinout on datasheets and boardviewer file it seems like APW8700 is the correct replacement as RT8809 has a bit different pinout.
Is it ok to get APW8700 ? also is there anyway to check whether the culprit really is the PWM controller IC ?

[daemon123]

Re: MSI GTX-980ti shorted MOSFET on memory rail

Update:
Sorry as i am noob and was not fully looking into the matter. Q48 was also shorted, now replaced both. Had display. Will reapply thermal paste and check the card thoroughly. Thanks again for help.
BTW can anyone explain what is doubler? which portion is it ?

[daemon123]

Re: MSI GTX-980ti shorted MOSFET on memory rail

update:
started pc and wanted to go to safe mode to get DDU but dooring boot the same thing. PC shut down. It was short lived. What could be the problem ? why are only those fets getting blown ?. Which confirm later if one or both are blow. Q47 Q48

[ktmmotocross]

Re: MSI GTX-980ti shorted MOSFET on memory rail

if u have bad controller u will blow them all and burn memory controller or some chips