Tightening heat sink screws in a cross pattern is important primarily because it helps to ensure that the thermal compound spreads evenly across the surface of the CPU or GPU. When screws are tightened in a linear or random fashion, it can lead to uneven pressure being applied to the heat sink, which may result in some areas making better contact than others. This uneven contact can create air pockets or gaps, preventing optimal thermal conductivity and leading to ineffective heat transfer away from the processor.
By using a cross pattern, the pressure is applied more uniformly, allowing the thermal paste to be evenly distributed. This uniformity is crucial for maintaining an efficient cooling system, as optimal heat dissipation is necessary for the longevity and performance of the components. Therefore, the main benefit of this method is to achieve a thorough and effective thermal interface, which directly impacts overall system stability and efficiency.