The iPhone 8 CPU is competitive with a Core i5
"Geekbench comparisons between phones and laptops used to be pretty meaningless, as the tests were not directly comparable, but that hasn’t been the case for some time now. Founder John Poole confirmed that it is legitimate to directly compare scores across platforms"
Look at these workloads[0] and tell me what doesn't look comparable across platforms? Parsing a 1.5MB HTML page, running SQLite queries, compiling code using LLVM, running Dijkstra's algorithm on a huge graph, repeatedly rendering PDFs, etc, etc.
[0] https://www.geekbench.com/doc/geekbench4-cpu-workloads.pdf
For such a claim to be true, you would have to expect that the phone CPU is somehow 10 times more efficient per Watt, while having the same kind of architecture (general CPU, not GPU/TPU/...).
Intel has not been optimizing for TDP/power draw as aggressively as Apple has. Apple started from that position and went up in performance. Intel started more in performance and had tried to keep TDP in check.
Apple A11 has 297 GFlops CPU performance. (1)
That “7th gen i5” is apparently i5-7360U. 32 FLOPs/cycle/core (2) * 2 cores * 3.50 GHz (=max turbo) = 224 GFlops.
> the phone CPU is somehow 10 times more efficient per Watt
Not 10 times. The i5’s TDP is just 15W. I don’t know about A11 but high-end Qualcomm chips can be up to 5-6W, just 3 times difference.
> while having the same kind of architecture (general CPU, not GPU/TPU).
That’s a continuum. They both CPUs, they both have SIMD that’s how they achieve that high flop/cycle, but the architecture can be quite different. A11 has 6 cores. Intel spends many transistors, and therefore energy, doing very complicated things: branch prediction, indirect branch prediction, cache synchronization between cores, speculative execution… Apple has full control over OS and software, they can probably get away with not doing some of these. Intel and AMD have to maintain compatibility with all software (including single threaded), built by all compilers and languages, that’s why they have fewer tradeoffs available to them.
What happens is that people see a benchmark and they see low power consumption and now conclude that it must have 10 times better performance per watt. x86 is bad, ARM is good
But the thing is you cannot have your cake and eat it too. The ARM SoC is clearly more efficient but only during standby or low intensity workloads and because everything is integrated into a single chip. As soon as you use a constant CPU/GPU intensive workload like servers or video games or even just google maps [1] you will have the same energy efficiency as intel chips.
[1] My phone battery barely lasts 2 hours with google maps