one is 928mb, and the other one is 960mb, wondering why there is such a difference?
And what is your ax3’s RAM size? please post reply, 
They came with different version it appears. You should upgrade both to stable and check again.
That is “… upgrade both to latest stable …” which is 7.11 as of time I’m writing this.
I have upgraded both ax3 to 7.11, but no any changes, still 928 & 960mb
Did you also upgrade routerboot firmware on both devices? (execute /system/routerboot/upgrade and reboot device).
yes no changes
Agree, it’s odd that two identical units have 32MB difference. While I suspect this isn’t going to be an issue, I don’t like oddities like this myself…
I take it config is default and no other packages are installed? Basically is config also identical? Certainly different feature being enabled use memory differently…
There was probably a faulty RAM chip at manufacturing so they disabled it rather than throw the whole package away. It’s possibly even something that’s detected on a startup memory test but usually that’s in the realm of ECC memory. I wouldn’t worry about it, 32mb isn’t going to make a big difference in usability.
Yes the settings are the same 
Well, good news is ECC is doing it thing. The rather exact 32MB difference also points in that direction too.
But I asked about config since if was hardware … not a lot you can do except return or accept the marginal difference .
waiting for the official reply 
Contact Mikrotik support via email if you want an official answer, this is a user support forum.
/system resource print
uptime: 18h17m6s
version: 7.11 (stable)
build-time: Aug/15/2023 06:33:51
factory-software: 7.5
free-memory: 478.1MiB
total-memory: 928.0MiB
cpu: ARM64
cpu-count: 4
cpu-frequency: 864MHz
cpu-load: 0%
free-hdd-space: 91.1MiB
total-hdd-space: 128.5MiB
write-sect-since-reboot: 741
write-sect-total: 36643
bad-blocks: 0%
architecture-name: arm64
board-name: hAP ax^3
platform: MikroTik
uptime: 1w3d22h33m12s
version: 7.11 (stable)
build-time: Aug/15/2023 06:33:51
factory-software: 7.5
free-memory: 594.4MiB
total-memory: 928.0MiB
cpu: ARM64
cpu-count: 4
cpu-frequency: 864MHz
cpu-load: 0%
free-hdd-space: 95.2MiB
total-hdd-space: 128.5MiB
write-sect-since-reboot: 1478
write-sect-total: 278547
bad-blocks: 0%
architecture-name: arm64
board-name: hAP ax^2
platform: MikroTik
it seems 928mb is the most common version. Maybe my two hap ax3 use different brands of RAM
I’d never looked at this. In a set that’s easy to check, I get the following:
7 with 928MB (5 are hAPax3, 2 hAPax2)
2 with 960MB (both hAPax2)
In case someone want to script it in bash/zsh:
user=admin; for x (10.99.100.31 10.99.100.41); ssh $user@$x ':put ([/system/resource/get total-memory] / 1024 / 1024)'
(change user= to your user & no I don’t use “admin” just for example 
)
Thx Bro
Thx mate
xiexie