Cold plate
Beginner
A metal plate with water flowing through it, pressed against a hot chip to carry the heat away.
Novice
A liquid-cooled heat exchanger mounted on a chip or module. Water or coolant flows through channels in the plate and carries away far more heat than air can.
Expert
Sized by heat flux (W/cm²), coolant flow and allowed temperature rise. It must stay in contact across the whole surface, which gets harder as the area and the thermal-expansion mismatch grow.
Explained in Wafer-scale and SRAM-heavy designs (Architectures).