Hmm seems like you're right and they have in fact improved, and with synchronous ones no less which should be really up there in efficiency. Then it really is a mystery why the Pi is still so energy inefficient when compared to other ARMs of similar capability.
It's worth noting too that the 28nm node is 10 years old now. [1] That's the biggest factor for power consumption. It's just a really cheap node to run now, which is why we're seeing it in stuff like Pi's. [2]
What are you comparing it against? Even the Pi 4 is Cortex-A72 on a 28nm process node. Pretty sure any other core that’s similar on those vectors will have approximately the same consumption. It’s just 6 year old tech now.
Most smartphones draw roughly one third of the power of an idling Pi at max load (without counting the screen draw), that's what I'm comparing against. I'd check some benchmarks, but the gap in consumption is so hilariously large I don't quite see the point.
Something like 6W for the Pi 4 and 2W for the average flagship smartphone chipset, both under max load if I recall right. Some of them even have double the core count.
Yes, well you're comparing silicon photolithography process nodes that are a decade apart and core architectures that are 5+ years apart, that's the difference. The Pi 4 is using Cortex-A72 cores, released in 2016 [1]. And is made on the 28nm node, released in 2011 [2][3][4]. Compare that to the Snapdragon 888, which uses the 5nm node (and the low-power version of it, at that), and Cortex-X1 cores from 2020. That's where your difference comes from. It's like comparing a Pentium III to a Core i7.
The Pi is cost-optimized to hit an entry level price target of $35. They have to use old cores and cheap lithography processes. High-end smartphones are cost-optimized for a $700-1200 price window with massive economies of scale and stiff competition, so they will naturally use the latest process nodes and cores. It's completely apples and oranges.
Compare the RasPi to other sub-$100 SBCs and it compares quite favorably.
There are lots of reasons the 28nm node has such longevity, mostly coming down to the fact it is the last silicon process node which uses simple gate topographies and is thus highly cost-effective to produce. [5][6]
If you want a Linux-capable SBC with similar cores to a recent mid-to-high-end smartphone, you need to look at the $400+ Nvidia Xavier NX or the $500+ Qualcomm RB5. Or get the $1400 Snapdragon 888 Developer Kit. Or wait til next year for the likely $1200+ Xavier Orin for something that's truly high-end.
