NVIDIA GPU Memory Chip ID and Replacement

[shovenose]

I'm trying to repair a GTX Titan X, seems to have a bad memory chip. I have this random graphic I found online but my card is double sided, does that matter? And based on the test result, which one do I need to swap?

I am using a Tesla M40 12GB as a donor board, model number of memory chips on that one is really hard to read but I think they are the same.

As for actually swapping a memory chip from the donor board, I have never done any BGA work before. I watched this video https://www.youtube.com/watch?v=goViV2IYogk and it seems he is using a new memory chip, vs I want to reuse the old one. So can I just apply liquid flux, use my generic SMD hot air gun thingy to heat it up, remove the chip, do the same with the donor card, plop it on there, and reheat it? Or do I have to do something with the solder balls or wick or what on earth do I do?

[diif]

Re: NVIDIA GPU Memory Chip ID and Replacement

Yes, memory chips need reballing. Old solder removed from both and new balls applied.
Northwest repair on YouTube is the one to watch.

[DynaxSC]

Re: NVIDIA GPU Memory Chip ID and Replacement

You definitely need to reball the replacement chip, as well as clean and slightly and equally tin the pad's on the pcb before płacing the chip for reflow soldering (tining pads is crucial for the success of the reflow proces in private lab conditions, as the access to professional more aggressive industry fluxes is very limited - they need to be used under special conditions and are not very healthy). All the fluxes available in retail shops are quite healthy but in my opinion not aggressive enough to give 100% reliable reflow connection of all pads w/o pretinned pads - this is at least my experience. You also need to preheat the board (set preheater to some 190-200 C), doing it without preheater is very difficult, too much heat must be applied from the top, so chip and board can be destroyed easily. You could try to do it only with just tining both chip and pcb with a solder iron as an emergency solution, but this is not the correct way, and nobody can say if this would work, and how long. You also need to take into account that pcb has no unlimited "lifes" for the reflow processes, with each heating wave the pcb is stressed a lot, so after a few attempts it may go broken for good (eg. pads gone off the pcb, soldermask get destroyed, vias get disconnected, etc. ). This depends also on the pcb quality, generally the older pcb, the less resistant they are, as technology was not so good 10 years ago. For one mem chip you can do the reballing even placing each tin ball manually on the chip pads with use of magnifier glass or microscope.

[ktmmotocross]

Re: NVIDIA GPU Memory Chip ID and Replacement

if u r not sure dont use used chip. buy new from ali.

[shovenose]

Re: NVIDIA GPU Memory Chip ID and Replacement

if u r not sure dont use used chip. buy new from ali.

OK, I bought a couple off eBay, so I don't have to deal with all the little balls.

Now I still have to figure out which chip to remove and replace?

You definitely need to reball the replacement chip, as well as clean and slightly and equally tin the pad's on the pcb before płacing the chip for reflow soldering (tining pads is crucial for the success of the reflow proces in private lab conditions, as the access to professional more aggressive industry fluxes is very limited - they need to be used under special conditions and are not very healthy). All the fluxes available in retail shops are quite healthy but in my opinion not aggressive enough to give 100% reliable reflow connection of all pads w/o pretinned pads - this is at least my experience. You also need to preheat the board (set preheater to some 190-200 C), doing it without preheater is very difficult, too much heat must be applied from the top, so chip and board can be destroyed easily. You could try to do it only with just tining both chip and pcb with a solder iron as an emergency solution, but this is not the correct way, and nobody can say if this would work, and how long. You also need to take into account that pcb has no unlimited "lifes" for the reflow processes, with each heating wave the pcb is stressed a lot, so after a few attempts it may go broken for good (eg. pads gone off the pcb, soldermask get destroyed, vias get disconnected, etc. ). This depends also on the pcb quality, generally the older pcb, the less resistant they are, as technology was not so good 10 years ago. For one mem chip you can do the reballing even placing each tin ball manually on the chip pads with use of magnifier glass or microscope.

Thank you, I will preheat the board, not the official way though

[piernov]

Re: NVIDIA GPU Memory Chip ID and Replacement

If you have never done this kind of rework before, something will go wrong and it's unlikely that you have the correct equipment.
As always better practice on donor boards.

lslightly and equally tin the pad's on the pcb before płacing the chip for reflow soldering.

That'll make the job harder. Pads can be cleaned and flattened by applying leaded solder then wicking, placing the chip will be much easier and it'll still get soldered properly.

You could try to do it only with just tining both chip and pcb with a solder iron as an emergency solution, but this is not the correct way, and nobody can say if this would work, and how long.

It won't even make contact with the board. That only works with flat ICs with only a handful of balls.