Shunt resistor keeps frying

[K404]

Hello all I have a GPU problem that i'm running short on ideas on how to solve.

 

It's an MSI GTX980 Gaming edition card, picked up faulty on eBay.

 

It briefly worked, but a shunt resistor fried under load. (Panasonic ERJ-M1WSF5M0U) i've replaced it twice, but insta-fry upon power up. Could there be damage to the current detection IC that the shunt is connected to? They are V3505's if i'm looking at this correctly... I don't know much about them and as of yet, I can't find spares.

 

I can find replacements for the shunt resistor and I've thought about buying higher-rated ones..... with a lower resistance for a power limit workaround..... but without having a better idea of what's wrong, I don't think that's very...... informed.

 

Any pointers would be very welcome Thanks.

 

K

[TerraRaptor]

Current sensing IC shouldn't be able to fry shunt. Most likely there is short circuit with mosfets. I would fix shunt, connect lab PSU to 12V rail, set it 1v 10A and check what is hot in VRM zone.

[K404]

Thankyou for the input on this I wasn't looking at the card correctly because I don't (yet?) have the experience with newer PWMs. Made some progress, but the card has had an awful life. It's currently not an 8-phase PWM, put it that way!