Perlmutter (#8) was just commissioned into full service earlier this year and uses Zen 3 cores with A100s. Leonardo (#4) is also current year and uses Xeon CPUs with A100s. Google's H3 also seems to pair H100s with Xeon CPUs.
But yes, the CPU is mostly just a footnote, most of the FLOPs come from the GPUs. Although of course the CPUs still need to be sufficiently fast enough that the GPUs can be kept fed.
IIRC, on Perlmutter's GPU partition, 60 of its 64PFLOPs are represented by the GPUs, with the remaing 4PFLOPs, being the CPUs. In comparison, their previous system Cori, had ~3PFLOPs in the Haswell partition and ~30PFLOPs on the KNL partition.
That, to me, indicates that CPU performance is mostly a footnote when GPUs are involved, as anyone who had previously been using Cori and is now on Perlmutter, will not see as dramatic of an improvement if restricted to CPUs but they would if able to use GPUs.
OK, fair :) Do you have any data on how many tasks are actually compute-bound?
From where I sit, we're often limited by memory bandwidth. When a CPU such as A64FX or even M2 shows up with decent bandwidth, lo and behold, they are often competitive. I do not understand why we didn't see something like SPR Max years ago.
But yes, the CPU is mostly just a footnote, most of the FLOPs come from the GPUs. Although of course the CPUs still need to be sufficiently fast enough that the GPUs can be kept fed.