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Blown MOSFET..

Timp74
Level 7
Hey, could anyone tell me what one of the MOSFETs does on ASUS X299 motherboards? It's the one marked in the attached photo of a Rampage VI Extreme. Only ASUS x299 motherboards seem to have a MOSFET like this. The Drain pin is connected to Vcore/Vccin and Source to ground I think, although that maybe a fault with the board I'm trying to fix. The MOSFET has blown and I can't work out what it does or if the PCB has a short to ground.
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6 REPLIES 6

restsugavan
Level 13
I think RMA or Exchange the board is better idea.
If you trying to do it will void the board warranty.
W11CANARY 26085.1 Core i9 7980XE 02007006 MCE ME 11.12.95.2499 R6E OFFICIAL BIOS 3801 SAMSUNG OG9 FW 1019.0 SSD 970 EVO PLUS 1 TB x 3 NVIDIA RTX 4090 GAME READY 551.86 64GB GSKILL DDR4 3200MHz JBL 9.1 Sound Bar DTS-X

restsugavan wrote:
I think RMA or Exchange the board is better idea.
If you trying to do it will void the board warranty.


I would if I could but the warranty is already void. 😉

Timp74
Level 7
The more important question for fixing the MB is if the PCB is shorted. Should the source on this MOSFET be connected to GND? If anyone could measure this on a working ASUS x299 board that would be great. The source is the three pins connected together on the left of the 4C06B (NTMFS4C06N) MOSFET in the photo. There is a similar MOSFET on some ASUS X99 boards too, and on some of them this MOSFET hasn't been populated. It is odd..

Braegnok
Level 14
It looks like perhaps the output to the VRM is shorted.

As shown on this Rampage VI Apex board, @ 4:00 min into video. https://www.youtube.com/watch?v=e-4nCAhaR9g

You might have some luck over at Badcaps Forums with what that chip does. https://www.badcaps.net/forum/

And or consider sending your board in for Repair Service to confirm if the PCB does indeed have a short.

Braegnok wrote:
It looks like perhaps the output to the VRM is shorted.

As shown on this Rampage VI Apex board, @ 4:00 min into video. https://www.youtube.com/watch?v=e-4nCAhaR9g

You might have some luck over at Badcaps Forums with what that chip does. https://www.badcaps.net/forum/

And or consider sending your board in for Repair Service to confirm if the PCB does indeed have a short.


Hey, I posted on an ASUS MB owners forum but haven't had much of a response. I'll give badcaps and go... Thanks.

Timp74 wrote:
Hey, I posted on an ASUS MB owners forum but haven't had much of a response. I'll give badcaps and go... Thanks.


Sorry I could not find any information on your motherboard as to exactly what that chip does, but due to it's location near the VRM and CPU, I would be concerned also with a short damaging the CPU.

I have sent a few boards to Badcaps repair service for cap and chip replacement they are a top notch shop, have a lot of smart folks on the forum.

Good luck, hope they can help you.