Hi there,
I have an Intel DX58SO motherboard that failed last year. One of the high side VRM MOSFETs failed shorted, and it killed my i7 980 CPU. This motherboard has a 6-phase VRM. The parts used on this motherboard's VRM are:
It was easy to figure out where the short was, because the bad MOSFET's gate was shorted to the drain/source too. Once I removed it, all the shorts were gone on the motherboard, and I confirmed on the removed MOSFET itself that the gate/drain/source were all shorted together. After figuring it out, I bought a new one from Digi-Key and soldered it on with my hot air station. I also got new thermal pads to apply to the VRM heatsinks and put everything back together with a Xeon W3680 (the less-expensive Xeon equivalent of the 980).
It worked fine for a while with very very light use, but earlier this year it failed again. I finally got around to looking deeper into it, and what I discovered is that the exact same MOSFET (the replacement I soldered on) failed in the exact same way again. I haven't tested yet if the Xeon was killed, but since it's a high side MOSFET, there's a high likelihood that it got fed 12V directly.
Anybody have any advice on what's going on here? Maybe I need better cooling on it? What would cause the replacement to fail in the exact same way?
When I read online about repairing a motherboard's VRM, I saw advice that you should typically replace the driver IC if a MOSFET shorts out, which I didn't do the first time because it was discontinued. I bought some from China this time and am waiting for them to arrive, so I can at least replace that chip this time as well.
What do you all think I should do this time around? My thinking is if I only replace the MOSFET again, it'll obviously fail again. It makes sense that the driver IC could be damaged since the gate was also shorted to 12V, so I'm guessing that's a good idea to replace this time too. I also bought a new diode, just in case. Are there any other best practices I should be following this time around? Should I also replace the low side MOSFET on the bad phase too? What about the MOSFETS on the other phases? I've seen some advice in the past in other threads about replacing other MOSFETs in the VRM at the same time. How far should I go? Any additional diagnostics I can perform? I've attached a picture of what the VRM circuit looks like, from the first time I repaired it.
One theory I have been floating around is that I have an aftermarket cooler (Cooler Master Hyper 212 EVO), and the fan on it doesn't blow straight down, so maybe the VRM isn't getting as cooled as it otherwise would with a stock Intel cooler.
This motherboard is old and not that great, but I think it is a fun project trying to repair it. It's definitely not worth the time it takes to fix, but I still want to give it a shot. Thank you for any advice!
I have an Intel DX58SO motherboard that failed last year. One of the high side VRM MOSFETs failed shorted, and it killed my i7 980 CPU. This motherboard has a 6-phase VRM. The parts used on this motherboard's VRM are:
- 6 x High side MOSFET: NTMFS4841NH
- 6 x Low side MOSFET: NTMFS4834N
- 6 x Driver: ADP3121JCPZ
It was easy to figure out where the short was, because the bad MOSFET's gate was shorted to the drain/source too. Once I removed it, all the shorts were gone on the motherboard, and I confirmed on the removed MOSFET itself that the gate/drain/source were all shorted together. After figuring it out, I bought a new one from Digi-Key and soldered it on with my hot air station. I also got new thermal pads to apply to the VRM heatsinks and put everything back together with a Xeon W3680 (the less-expensive Xeon equivalent of the 980).
It worked fine for a while with very very light use, but earlier this year it failed again. I finally got around to looking deeper into it, and what I discovered is that the exact same MOSFET (the replacement I soldered on) failed in the exact same way again. I haven't tested yet if the Xeon was killed, but since it's a high side MOSFET, there's a high likelihood that it got fed 12V directly.
Anybody have any advice on what's going on here? Maybe I need better cooling on it? What would cause the replacement to fail in the exact same way?
When I read online about repairing a motherboard's VRM, I saw advice that you should typically replace the driver IC if a MOSFET shorts out, which I didn't do the first time because it was discontinued. I bought some from China this time and am waiting for them to arrive, so I can at least replace that chip this time as well.
What do you all think I should do this time around? My thinking is if I only replace the MOSFET again, it'll obviously fail again. It makes sense that the driver IC could be damaged since the gate was also shorted to 12V, so I'm guessing that's a good idea to replace this time too. I also bought a new diode, just in case. Are there any other best practices I should be following this time around? Should I also replace the low side MOSFET on the bad phase too? What about the MOSFETS on the other phases? I've seen some advice in the past in other threads about replacing other MOSFETs in the VRM at the same time. How far should I go? Any additional diagnostics I can perform? I've attached a picture of what the VRM circuit looks like, from the first time I repaired it.
One theory I have been floating around is that I have an aftermarket cooler (Cooler Master Hyper 212 EVO), and the fan on it doesn't blow straight down, so maybe the VRM isn't getting as cooled as it otherwise would with a stock Intel cooler.
This motherboard is old and not that great, but I think it is a fun project trying to repair it. It's definitely not worth the time it takes to fix, but I still want to give it a shot. Thank you for any advice!
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