As the name suggests, the heatpipes in a HDT cooler are placed in the base of the cooler and gaps will normally be present between the base and the heatpipes. This results in a lower surface area of contact when the base touches the CPU which will in turn reduce the cooler's thermal efficiency. To solve this problem Xigmatek's Xi-3 thermal compound was designed specifically for HDT coolers and features smaller, more dense particles. The Xi-3 is rated at 104 Pa·s, specific gravity at 2.5 g/cm³, 9.1 W/mK thermal conductivity and features an anti-bleed composition.
As with most other compounds on the market, the compound is non-electrically conductive and will be sold in a 4 g syringe for a currently unknown price.