Best place to source RAM chips? 8GB 820-00850 boards to 16GB or 32GB

[ugamazing]

I'm looking to upgrade several 8GB 820-00850 boards to 16GB or 32GB for personal use. I am curious what the best practice and process is for sourcing new replacement chips, and what vendor(s) you guys prefer? Another question is, how do I find compatible chips and their corresponding part/model numbers? For example, in the 820-00850 schematic, the DDR chip U2600 model listed (EDFB232A1MA) corresponds to 1x32GB chip. Of course, I would need 4x8GB chips to replace the 4x2GB chips currently on the board. How do I find compatible 8GB chips? Is it as simple as searching "BGA178 8GB 2133" and buying 4 of them?

For example, I found these chips on Aliexpress, but what capacity are they? Where is that information provided (for ANY replacement RAM chips)? None of these vendors seem to put the actual single-chip capacity (i.e. 2GB, 4GB, 8GB, etc) in the descriptions. Am I missing something very obvious here? I'm trying to learn, haha!

I am also curious about upgrading the RAM on 820-01521 boards, from 8GB to 16GB. I have already swapped 16GB RAM from dead boards to working 820-01521 boards without issue, but I have quite limited supplies of dead 16GB boards (of course), and I would like to buy new 16GB RAM sets to install instead of pulling from other boards. These chips are much different compared to what I'm used to seeing with RAM chips, package BGA253. I haven't been able to find the "exact" replacement (H9CCNNNFAGML), but have found similar chips, i.e. H9CCNNN8KTML. Would these chips be compatible? Also, again, is there a way to determine the exact memory capacity of these chips? I can't seem to find that (seemingly-basic) info on any of the source pages I've found these chips on.

So, in short:

1. What is the best way to determine compatible chips (suitable replacements, etc) for particular board models?
2. What is the best place to order these new/replacement chips?
3. What is the best way to determine the capacity of these replacement chips?

All help and advice appreciated!

[piernov]

Re: Best place to source RAM chips? 8GB 820-00850 boards to 16GB or 32GB

The selected SPD profile has to match the chip on the board. It could still boot with slightly different parameters but hard to tell and could be unstable. Datasheet would tell all the details including density of course but sadly most of them are not available.
SPD profiles are stored in the UEFI. With T2 machines it's not possible to tweak that (as far as I know) so you have to use one of the RAM part number used by Apple and adjust strapping resistors accordingly.
Documenting which chip is on which board with which configuration would help.
As for the RAM used on 2018-2020 MacBook Air, I don't know of any other machine using x64 ICs, so the supply for these chips may be coming from MBA donor boards.
As for a reliable supply, no idea. Aliexpress has lots of garbage as usual, maybe there's something good in there… Some vendors may be able to answer questions but usually they have no idea about what they're selling.

[ugamazing]

Re: Best place to source RAM chips? 8GB 820-00850 boards to 16GB or 32GB

Thanks so much as always, PE! I'm going to do some tests with some different things; will report back if I find anything of use.