Poor temperature uniformities and high pumping powers due to large pressure drops are the major drawbacks of the conventional microchannel cooling solutions. In this work, a liquid cooling device based on a matrix of microfluidic cells is presented. The coolant flow rate in each microfluidic cell is individually tailored, through thermally activated microvalves, to the local heat extraction needs in order to improve the temperature uniformity and avoid overcooling. A numerical study is implemented to assess the thermo-hydraulic performance of the cooling device. The analysis is performed in a steady state CFD study and integrated along a time dependent and non-uniform heat load scenario. The results show an enhancement of the temperature uniformity along the whole system while reducing the energy needed for the pumping power by 89.2% compared to the conventional microchannel technology.