Pi 4 RAM chip identification

[tonyhansen]

The only visible difference between different models of the Pi4 in terms of RAM appears to be a code on the RAM chip itself.

I have a limited sample, but the codes I have seen so far have been:

2GiB 9LD77 D9WHZ (sample of 1)
4GiB 9FD77 D9WHV (sample of 4)
8GiB OAA47 D9ZCL (sample of 2)

Can anyone confirm if these codes are indeed consistent across all versions of the specific RAM sizes? Or at least part of the code? If only part of the code is consistent, which portion?

If no portion of the code is consistent, is there another way of visually identifying the RAM size without booting up the board?

For completeness, what codes appeared on the 1GiB RAM chips?

[bassamanator]

This is me:

8GiB OAA47 D9ZCL

[ejolson]

This is me:

8GiB OAA47 D9ZCL

As far as I know all Pi 4B computers are built with Micron Technology RAM chips. Every time I use the Pi it brings back fond memories of upgrading my 486 PC with 4 sticks of RAM also manufactured by Micron. That system ran Linux kernel 1.2.13 and originally had only 8MB RAM. After the upgrade it had 20MB so that X Windows ran almost as smoothly as it does now on the Pi. Video playback on the Pi, however, is much better.

[drgeoff]

Currently there are visible differences in layout between the 8 Gbyte version and all others in the area between the AV jack and the USB sockets.

[tonyhansen]

Currently there are visible differences in layout between the 8 Gbyte version and all others in the area between the AV jack and the USB sockets.

Are these layout differences specific to the use of 8GiB or will those layout changes be used going forward with other RAM models as well?

[timg236]

Currently there are visible differences in layout between the 8 Gbyte version and all others in the area between the AV jack and the USB sockets.

Are these layout differences specific to the use of 8GiB or will those layout changes be used going forward with other RAM models as well?

From time to time components are swapped on a board without it being a new board revision. We don't comment on it or announce it and the numbers on the SDRAM chip are the SDRAM manufacturers own version id.

The 8GB has a new power supply and removes the dedicated VLI EEPROM both of which required firmware and Linux changes. This will account for many of the visible differences that you mention.

Again, we don't pre-announce when or indeed if major board revision changes will happen.

[ejolson]

Currently there are visible differences in layout between the 8 Gbyte version and all others in the area between the AV jack and the USB sockets.

Are these layout differences specific to the use of 8GiB or will those layout changes be used going forward with other RAM models as well?

Now that the local casinos are open to prepare the way for a second wave, I'd place bets on all the 4B models going with a new happy-face circuit board over time. Unfortunately, the payout is given in US$ rather than something more lasting in value like a quantity of Pi computers.

[tonyhansen]

Thank you -- my take from that is that the chip layout changes will likely migrate to the other RAM configurations too.

So, can anyone confirm if these codes are indeed consistent across all versions of the specific RAM sizes? Or at least part of the code? If only part of the code is consistent, which portion?

2GiB 9LD77 D9WHZ
4GiB 9FD77 D9WHV
8GiB OAA47 D9ZCL

Thanks!

[wildfire]

Asked and answered, see Timg's earlier post in this thread.

[ejolson]

Thank you -- my take from that is that the chip layout changes will likely migrate to the other RAM configurations too.

So, can anyone confirm if these codes are indeed consistent across all versions of the specific RAM sizes? Or at least part of the code? If only part of the code is consistent, which portion?

2GiB 9LD77 D9WHZ
4GiB 9FD77 D9WHV
8GiB OAA47 D9ZCL

Thanks!

The Micron FBGA code for the 1GB chip is still missing. Have you tried looking it up?

https://www.micron.com/support/tools-and-utilities/fbga

Then use

https://media-www.micron.com/-/media/cl ... umdram.pdf

to interpret the full part number.

[W. H. Heydt]

I have a P4B1. Looks like the marking on the RAM package is E9F0 7181C. (That took +2.0 reading glasses AND a magnifying glass.)

[ejolson]

I have a P4B1. Looks like the marking on the RAM package is E9F0 7181C. (That took +2.0 reading glasses AND a magnifying glass.)

Who is the manufacturer?

[tonyhansen]

Thank you everyone for the information. Thank you especially to @ejolson for providing the "magic decoder ring" URLs.

To summarize the information so far:

These are Micron Technology "Mobile LPDDR4" RAM chips.

The first part of the code below contains a FBGA Date Code, so 9F would be 2019/week 12, 9L would be 2019/week 24 and 0A would be 2020/week 2. I'm not sure what the remainder of that code refers to.

The last part of the code is the FBGA code for a part number.

Code: Select all

2GiB date: 9LD77 part#: D9WHZ
4GiB date: 9FD77 part#: D9WHV
8GiB date: OAA47 part#: D9ZCL 

@W. H. Heydt gave a code of 7181C for their 1GiB RPi4. Unfortunately, that code does not resolve on the FBGA lookup page. Can anyone else confirm that code? @ejolson asks

Have you tried looking it up?

I did indeed try; however, there are a few parts that be the ones used. It would be better to find the actual part numbers used on the boards.

@timg236 reminds us that parts can be changed periodically, as well as board layouts, so it is not guaranteed that future 2GiB, 4GiB and 8GiB models will continue to use the same RAM parts.



However, it HAS been confirmed that: YES, the amount of RAM on the board CAN be determined by looking at the part # portion of the code on the RAM chip, as per the above chart.

Thank you again for everyone who helped answer my questions.



References: (with thanks again to @ejolson for some of these)

Date codes reference: https://media-www.micron.com/-/media/cl ... 2ae2f13f5c

Part number references (FBGA lookup page): https://www.micron.com/support/tools-and-utilities/fbga

Interpreting full part numbers: https://media-www.micron.com/-/media/cl ... umdram.pdf