The 16GB flavour will have a 12-layer PCB, while the 12GB model would have a 10-layer PCB.
This means that the RTX 4080 with 16GB would have a 256-bit bus, while the 12GB model would come with a trimmed 192-bit bus and Nvidia will have to raise the specs of other sections to compensate.
According to the data provided by MEGAsizeGPU, the 4090 model will have 24GB of GDDR6X memory with a 14-layer PCB, more complex than that of the RTX 4080. The RTX 4090 graphics card will have a TBP of 450W, while the RTX 4080 would have a TDP of 350 TBP.
The RTX 4090 will probably see the light of day in October. We don’t know if the RTX 4080 and 4070 will launch this year or have to wait until 2023.