My knowledge isn't current enough to offer more than speculation. However, something like an 80286 didn't even require a heatsink, while my 80486 had a dinky h

My knowledge isn't current enough to offer more than speculation. However, something like an 80286 didn't even require a heatsink, while my 80486 had a dinky heat sink similar to what you might find on a modern motherboard chipset. At the same time, on a micron node, wires were huge. A few special cases aside (DEC Alpha comes to mind), power distribution didn't require anything special beyond what you'd see on your signal wires, and wasn't a major part of the interconnect space. Mapping out to 2024: 1) Signal wires became smaller than ever. 2) Power density is higher than ever, requiring bigger power wires. So there is a growing disparity between the needs of the two. At the same time, there is continued progress in figuring out how to make through-wafer vias more practical (see https://en.wikipedia.org/wiki/Three-dimensional_integrated_circuit https://en.wikipedia.org/wiki/Three-dimensional_integrated_c...). I suspect in 2000, this would have been basically restricted to $$$$ military-grade special processes and similar types of very expensive applications. In 2024, this can be practically done for consumer devices. As costs go down, and utility goes up, at some point, the two cross, leading to practical devices. I suspect a lot of this is driven by progress in imagers. There, the gains are huge. You want a top wafer which is as close as possible to 100% sensor, but you need non-sensor area if you want any kind of realtime processing, full frame readout (e.g. avoiding rolling shutter), or rapid readout (e.g. high framerate). The first time I saw 3D IC technology in mainstream consumer use were prosumer-/professional-grade Sony cameras. I have strong fundamentals, but again, I stopped following this closely maybe 15 years ago, so much of the above is speculative.