The old Cascade Lake based server found by the previous poster is still new enough to have instructions for relatively fast AI inference with the INT8 format.

So for optimal speed the models must be quantized in this format.

It is very likely that with INT8 models those CPUs are fast enough so that the inference throughput is limited by the memory bandwidth (384-bit interface to DDR4-2933 per socket, i.e. 282 GB/s for both sockets).

The memory throughput for such an old server is very similar to an AMD Ryzen Strix Halo, NVIDIA DGX Spark or Apple M5 Pro, but it has much more memory.

The inference speed should be very similar to those, but with bigger LLMs.