Dying EVGA 980 TI GPU--need help identifying a component - Page 1
Forum section: electronics / repair

author: usinjin
author_rank: Newbie
timestamp: January 15, 2019, 05:06:54 am
content: 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.

author: fzabkar
author_rank: Super Contributor
timestamp: January 15, 2019, 08:20:20 am
content: Q24 is probably a MOSFET.

author: usinjin
author_rank: Newbie
timestamp: January 15, 2019, 08:58:59 am
content: 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-burnsOn 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/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

author: jerb
author_rank: Contributor
timestamp: January 15, 2019, 02:09:28 pm
content: I have a 1080ti im working on right now. Might not be the same mosfet but i can look to see what it is.

author: usinjin
author_rank: Newbie
timestamp: January 22, 2019, 07:08:19 am
content: Quote from: jerb on January 15, 2019, 02:09:28 pmAny luck?

author: azpcrepair
author_rank: Newbie
timestamp: January 26, 2019, 06:16:59 pm
content: 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 GA5U1XI attached the pic, Hope it help

author: fzabkar
author_rank: Super Contributor
timestamp: January 26, 2019, 08:11:31 pm
content: AON7403, Alpha & Omega, P-ch MOSFET, -30V, -29A, 18mOhm Rdson, DFN 3x3_EP:http://www.aosmd.com/pdfs/datasheet/AON7403.pdf

author: TrickyNekro
author_rank: Frequent Contributor
timestamp: January 26, 2019, 09:19:20 pm
content: 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...

author: usinjin
author_rank: Newbie
timestamp: January 26, 2019, 09:49:34 pm
content: Quote from: azpcrepair on January 26, 2019, 06:16:59 pmAwesome 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

author: usinjin
author_rank: Newbie
timestamp: January 26, 2019, 09:50:12 pm
content: Quote from: TrickyNekro on January 26, 2019, 09:19:20 pmYep, especially these "SC" boardsBoard is probably trash but it was fun playing with it, it was super cheap