Minimal half size cpu add-on card without vga or ram?

[vexatious]

Looking for an x86-64 cpu add-on without vga and extra peripherals. Most have sata, vga, sound and what not but I only need the cpu. Must also be able to share system ram or have dedicated ram work as a mounted ram drive on a desktop motherboard (standard ATX with PCIE 16X slots). Basically want to offload certain tasks to an extra cpu to keep main cpu cores from getting overworked. Want to do this as simple as possible ( like using taskset to assign PID and child processes to the add-on cpu).

Regards
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Gentoo
Slackware