The thin iMacs didn’t have any room for that, so Apple added a memory access door to the back of the machine, but only on the 27-inch models, as noted by this support article: Memory is not removable ...
However, it's great news for those lamenting the loss of the 27-inch iMac in the ... Hopefully, this will result in a 32-inch iMac to be unveiled in late 2024. If not, we should see something ...