> actually have the good chips.

Has that ever been the case yet, for ARM servers?

There's no "magic" in ARM. The reduced power comes from the reduced complexity. Heck, branch prediction is fairly new in ARM. I have trouble seeing a time when an Intel chip will ever fall behind even a bucket full of ARM chips, unless workloads ever fall near zero.

Reduced power comes from reduced complexity, and that has a performance cost, yes -- but it takes far more than a 10% increase in power to get a 10% increase in performance.

Intel's designs, being tuned for high sequential performance, are significantly better for that purpose; but if you look at VPS services which currently only get a fraction of a CPU each, I'm sure they could run more power-efficiently with a larger fraction of a punier CPU.

What's the difference between 100 ARM CPUs @ 1 watt versus one Intel CPU @ 100 watt, except that you need a bigger data center for the ARMs?

There are a lot of nice things in arm. Ie slightly less register renaming.

For example, Jim Keller estimates a fully developed arm chip will be 15-30% more efficient than an equivalent x86. Now, this development hasn't happened yet, but with giants like Qualcomm, it will happen eventually.

If this was the case (and there weren't other issues e.g. insturctuon fusion etc) then wouldn't AMD be pushing K12 far harder? It's the same ceneteral core as Zen but they don't seem to have as much confidence in it.

Because migration is super expensive and a big part of what's preventing the movement to ARM servers. Also, the aforementioned case hasn't necessarily happened, Keller has spent forever making Zen better. They are still working on K12 IIRC, but Ryzen, for good reason, is the focus. Besides, CPUs are more and more becoming simply host systems.

Besides, never doubt the word of jim keller ;)

The magic in arm is in Risc. in an azure (or aws) cloud where 90% of operations are webserver events, those are less than complex operations. Relational databases with sums, grouping, etc. Not using every bit of x86. And once you start talking about geospatial, advanced searching, and cryptography, you might just offload to a graphics chip.

What is this, the 90s? No one cares about RISC vs CISC or ARM vs. x86-64 (on a high-level ISA level) anymore. It's all in the implementation.