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Electronics => Repair => Topic started by: usinjin on January 15, 2019, 05:06:54 am

Title: Dying EVGA 980 TI GPU--need help identifying a component
Post by: usinjin on January 15, 2019, 05:06:54 am
Hello all,

On a whim, I purchased a dead 980 TI SC to play with. With the card installed in a computer, it would trip the computer's PSU. With the 6 + 8 pin power rails disconnected, the computer would turn on, and the card would display a message saying to turn off the computer and plug in the PCI-E power connectors. So a short on on of the rails. Maybe not totally dead.

I guessed that one of the MOSFETs was bad. After removing a few, I tested for the short and it was gone. I ordered replacement MOSFETs (SIC789) and replaced them. Low and behold, the computer posted and I got my desktop. I installed a driver without a hitch. Temps looked stable. I crossed my fingers and ran a mild stress test. Immediately, I lost the display signal and smelled burning electronics. Darn! I pulled the card and immediately found the burned chip. Unfortunately there's only one of them it seems, and because it's burned I can't read what it is. I am writing to see if anyone knows what the chip is or how I can figure it out. In an attempt to figure it out I've zoomed into all the 980 TI PCB images I can find, but no luck on reading it. From a video it seems like it's a voltage controller/regulator for the VRAM. See attached image.

I realize the card is probably not worth a ton of effort and very well could burn up additional chips once I re-power it, but it's been fun fixing it anyways and I'd hate to give up now.
Title: Re: Dying EVGA 980 TI GPU--need help identifying a component
Post by: fzabkar on January 15, 2019, 08:20:20 am
Q24 is probably a MOSFET.
Title: Re: Dying EVGA 980 TI GPU--need help identifying a component
Post by: usinjin on January 15, 2019, 08:58:59 am
Just for reference, here is a picture of someone else's EVGA 980TI (boy these do seem to burn up a lot..)

https://www.mmo-champion.com/threads/2235693-EVGA-GTX-980TI-catches-fire-and-burns (https://www.mmo-champion.com/threads/2235693-EVGA-GTX-980TI-catches-fire-and-burns)

On page 1, on the image, Q24 is on the bottom-left side/corner area.

Also, from here: https://forums.guru3d.com/threads/where-to-order-gpu-mosfets.359311/ (https://forums.guru3d.com/threads/where-to-order-gpu-mosfets.359311/)

The manufacturer identifies Q24, but the card is a 570. It's the same package, but of course that isn't a guarantee that they're the same spec. rats
Title: Re: Dying EVGA 980 TI GPU--need help identifying a component
Post by: jerb on January 15, 2019, 02:09:28 pm
I have a 1080ti im working on right now. Might not be the same mosfet but i can look to see what it is.
Title: Re: Dying EVGA 980 TI GPU--need help identifying a component
Post by: usinjin on January 22, 2019, 07:08:19 am
Quote from: jerb on January 15, 2019, 02:09:28 pm
I have a 1080ti im working on right now. Might not be the same mosfet but i can look to see what it is.

Any luck?
Title: Re: Dying EVGA 980 TI GPU--need help identifying a component
Post by: azpcrepair on January 26, 2019, 06:16:59 pm
Hi,
I have same video card and Have exactly same problem.
I have to replace Sic789 but don't know where to buy them. where are you buy Sic789?

the Q24 is 7403 GA5U1X

I attached the pic, Hope it help
Title: Re: Dying EVGA 980 TI GPU--need help identifying a component
Post by: fzabkar on January 26, 2019, 08:11:31 pm
AON7403, Alpha & Omega, P-ch MOSFET, -30V, -29A, 18mOhm Rdson, DFN 3x3_EP:
http://www.aosmd.com/pdfs/datasheet/AON7403.pdf (http://www.aosmd.com/pdfs/datasheet/AON7403.pdf)
Title: Re: Dying EVGA 980 TI GPU--need help identifying a component
Post by: TrickyNekro on January 26, 2019, 09:19:20 pm
Hope it´s only the MOSFET though and not the driver also.... that could get complicated fast...

But I will get another chance to trash consumer products... they are build to burn after some time... -29A... Seriously... on rails that can drain 200A... shame... big shame...
I know it´s phased but still it´s so less... so less... and p-channel at these currents... All consumer products are cancer... just cancer...
Title: Re: Dying EVGA 980 TI GPU--need help identifying a component
Post by: usinjin on January 26, 2019, 09:49:34 pm
Quote from: azpcrepair on January 26, 2019, 06:16:59 pm
Hi,
I have same video card and Have exactly same problem.
I have to replace Sic789 but don't know where to buy them. where are you buy Sic789?

the Q24 is 7403 GA5U1X

I attached the pic, Hope it help

Awesome thanks for that! The sic789 I ordered from here: https://www.mouser.com/ProductDetail/vishay/sic789cd-t1-ge3/?qs=k27q3RmtXoZZlarW9ZaI3Q%3d%3d&countrycode=US&currencycode=USD (https://www.mouser.com/ProductDetail/vishay/sic789cd-t1-ge3/?qs=k27q3RmtXoZZlarW9ZaI3Q%3d%3d&countrycode=US&currencycode=USD)
Title: Re: Dying EVGA 980 TI GPU--need help identifying a component
Post by: usinjin on January 26, 2019, 09:50:12 pm
Quote from: TrickyNekro on January 26, 2019, 09:19:20 pm
Hope it´s only the MOSFET though and not the driver also.... that could get complicated fast...

But I will get another chance to trash consumer products... they are build to burn after some time... -29A... Seriously... on rails that can drain 200A... shame... big shame...
I know it´s phased but still it´s so less... so less... and p-channel at these currents... All consumer products are cancer... just cancer...
Yep, especially these "SC" boards  ;D

Board is probably trash but it was fun playing with it, it was super cheap