Here’s an X-ray of the 24-inch iMac. [credit:
One thing to keep in mind: there is a version of the 24-inch iMac with seven GPU cores and another with eight. iFixit is tearing down the eight-core version, and that’s relevant because the cooling system differs between the two, so this isn’t exactly representative of every 24-inch iMac Apple is shipping.
Most of the components, including the logic board, can be found in the iMac’s chin. Since this is an M1 Mac, there is obviously not a separate GPU, and most of the key components are on the SoC. That means that upgrading the RAM or the GPU is not a possibility. iFixit compares the logic board to that found in the M1 MacBook Air.