Computer Goods/Electronics/MDU1516 Mosfet smoking
This is on an HP 702176-501 motherboard in a HP Envy M6-1205dx laptop.
Laptop was bought on e-bay for parts or not working. I found it had a broken screen and no charger. I bought both and the laptop was working, fan was running.
Doing what I normally do with these laptops I add RAM, an SSD, upgrade the CPU if possible and clean the CPU cooler and apply new thermal paste.
I was testing the new RAM one stick failed HP's built in test so I ran Memorytest 86 v6, which the same stick failed. the other stick passed both tests in the same slot or slot 1. I was testing a second time as I was getting ready to return the RAM and wanted to be sure and suddenly the computer shut down. I turned it on again and got ready to test then saw a whiff of smoke. Further investigation shows solder bubbling on one side of a mosfet (MDU1516). PQ2001 is the motherboard manufacturers number printed below this mosfet on the PCB. The mosfet is one of five grouped near the rear side of the CPU socket. Each has eight connections to the PCB only the bottom four had solder bubbling on PQ2001. My guess is that these are the power mosfets for the CPU.
As a side note: Early on I had removed about a tablespoon of Thermal Interface Material from the CPU and heatsink. A huge amount. It was touching many of the components of the CPU. I cleaned with alcohol and replaced that with a more reasonable amount, 3/16 diameter blob in the center and tightened the heat sink on following the 1,2,3,4 sequence. The laptop was running fine and I could feel the fan was dissipating lots of heat from the exhaust port.
My question is: if I replace that mosfet is that likely to fix the problem? Did the fan stop at some point and I didn't realize it? Is it a problem in the charging circuit like a bad power supply?
you can try replacing the mosfet, however I think there might be more wrong with it than just a bad chip.
Usually when motherboards fail its due to a much bigger problem (lots of capacitors, bad components, etc), I've seen them where some desktops will pop half the capacitors on the motherboard and keep running, others I've seen 1 or 2 pop and the computer refuses to turn on. over all I'd say save your time and money and get another computer.