Two running Rosetta work.
Four running Rosetta work.
Three running Rosetta and ten running Einstein BRP4 work.
The farm currently consists of:
2 x Ryzen 3900X machines (the CPU only)
6 x i7-8700 machines (the Intel GPUs)
4 x Ryzen 3600 machines with GTX 1660 Ti graphics (the Nvidia GPUs)
As you can see from the farm status its concentrating on Rosetta work. The new Ryzen 3900X is building up its RAC (Recent Average Credit). The older one seems to have topped out at 31,000 credits for Rosetta so that is where I would expect the newer one to settle, its on 19,000 at the moment.
I made an inquiry to Ampere Computing regarding an Altra-based machine. They make ARM v8.2 multi-core CPUs with various clock speeds. I haven't received an answer.
Ampere Computing have two models of fully assembled machines. The single CPU (80 cores) machine is a 2U rack mount with a Gigabyte motherboard, its called Mt Snow. There is also a dual CPU (160 cores) in a 2U rack mount. Its called Mt Jade. Both support PCIe gen 4 and use standard DDR4-3200 memory.
There is also the Marvell ThunderX3 chip which supports more cores but isn't quite available yet. It too is an ARM v8 multi-core CPU with hyper-threading.