Host CPU
Beginner
The server’s main, all-purpose processor. It runs the machine and hands big math jobs to the accelerators.
Novice
The central processing unit that boots the machine, runs the operating system and the program’s control logic, and talks to every other device. In an AI server it prepares data and launches work on the accelerators.
Expert
The CPU socket(s) whose root complex owns the PCIe hierarchy, the main DRAM channels and the I/O memory map. Its lane count, memory bandwidth and core count bound how many devices it can feed and how fast it can stage data for them.
Explained in Board and server (Systems).
See also: Root complex, AI accelerator (GPU, NPU).