Gigabyte GTX 980 Ti G1 Gaming

[homesync]

I've bought a defective Gigabyte GTX 980 Ti G1 Gaming. Lights turn on and fans spin, but no display. A visual inspection of the PCB resulted in 2 suspicious looking mosfets located on Q29 and Q32 of the board. They both have solder leaking out. The part number on both of them is F DE48AA (22CA N7CC). I couldn't find this specific mosfet or relevant information about it so I reached out to onsemi for help. They responded quickly and told me this mosfet was probably custom made for Gigabyte and/or discontinued before they acquired Fairchild. They couldn't help me. My main question is: Do i need another G1 Gaming to transplant the mosfets or can i use an alternative? And if the latter is the case, can someone point me in the right direction?
Or is it possible that the mosfets survived the heat that caused the solder to melt in the first place?

I've read that this area of the PCB often causes problems for this GPU.

[sikocan]

Re: Gigabyte GTX 980 Ti G1 Gaming

This could be the MOSFET you need
https://s.click.aliexpress.com/e/_DcwYIIx

[homesync]

Re: Gigabyte GTX 980 Ti G1 Gaming

This could be the MOSFET you need
https://s.click.aliexpress.com/e/_DcwYIIx

Thanks very much. I will check it out!

[DynaxSC]

Re: Gigabyte GTX 980 Ti G1 Gaming

Solder leakings must not mean the mosfets are bad, this can be remains from the production process. Check first if all voltages are present or not. Then you should desolder and check the mosfets, before ordering new and burning your money. Post a picture, this will tell us more. Shorted mosfets usually have some visible demage on the plastic, or in severe cases the pcb is burned under them and the mosfet is melted with the pcb copper making it very difficult to remove. If the short lead to very high temperature, the pcb underneith might be burned and shorted (leads to an electric arc), this is usually easy visible and possible to smell and finally in most cases not repairable. Finally mosfets can be usually replaced with better ones, having at best same voltage, higher ampere rating and lower RDSon, and same case/pin layout, but then you need to replace all the mosfets in that section. This way you also improve the reliability/efficiency and lower the power losses and working temperature (RDSon param. as low as possible) of the VRM. Vendors often use as cheap as possible parts, on the limits of the design parameters, so they fail too early, as the parts although very slowly, but loose their paramemters. Also even new mosfets (electronic devices in general) can have a significant parameter dispersion, so in worst case it can happen that the weakest fails in high load conditions, as the load is not distributed between the mosfet in the VRM evenly. Also electrostatic power surges when VRM is working can lead to such a fatal VRM failure, easy to do eg. with connecting monitor to card when the card is powered and working.

[homesync]

Re: Gigabyte GTX 980 Ti G1 Gaming

Solder leakings must not mean the mosfets are bad, this can be remains from the production process. Check first if all voltages are present or not. Then you should desolder and check the mosfets, before ordering new and burning your money. Post a picture, this will tell us more. Shorted mosfets usually have some visible demage on the plastic, or in severe cases the pcb is burned under them and the mosfet is melted with the pcb copper making it very difficult to remove. If the short lead to very high temperature, the pcb underneith might be burned and shorted (leads to an electric arc), this is usually easy visible and possible to smell and finally in most cases not repairable. Finally mosfets can be usually replaced with better ones, having at best same voltage, higher ampere rating and lower RDSon, and same case/pin layout, but then you need to replace all the mosfets in that section. This way you also improve the reliability/efficiency and lower the power losses and working temperature (RDSon param. as low as possible) of the VRM. Vendors often use as cheap as possible parts, on the limits of the design parameters, so they fail too early, as the parts although very slowly, but loose their paramemters. Also even new mosfets (electronic devices in general) can have a significant parameter dispersion, so in worst case it can happen that the weakest fails in high load conditions, as the load is not distributed between the mosfet in the VRM evenly. Also electrostatic power surges when VRM is working can lead to such a fatal VRM failure, easy to do eg. with connecting monitor to card when the card is powered and working.

Thanks for al the helpful information. I will inspect the area again and try to make a picture (my microscope has no camera).

[homesync]

Re: Gigabyte GTX 980 Ti G1 Gaming

This is a picture from techpowerup. The mosfets are in the bottom right. As i said before, i will try to post a picture of my own board asap.

[homesync]

Gigabyte GTX 980 Ti G1 Gaming

And here are my own photos

[MrzPdlch]

Did you happen to solve the problem with the Mosfet? And were you also able to find a proper schematics for the card?
I have one here with two blown fuses and I wonder which ones I need to replace it.