Direct Touch Heat Pipe (HDT)

Direct Touch (HDT — Heat Pipe Direct Touch) coolers expose polished, flattened copper heat pipes directly to the CPU IHS surface, eliminating the traditional copper or aluminium base plate and one thermal interface layer. This reduces thermal resistance between the CPU's IHS and the heat pipes by approximately 0.05°C/W. HDT designs appear in Cooler Master Hyper 212 (generation 1), Arctic Freezer 34, Noctua NH-U12A (indirect HDT derivative), and DeepCool Gammaxx series. The trade-off is that pipe layout must carefully cover the CPU die location, which varies between Intel and AMD socket positions.