An electronic rack of a data center, comprising: a plurality of computing nodes (203 A, 203B, 203C, 203D, 203E) arranged in a stack, each computing node containing at least one processor attached to a liquid cold plate ; a plurality of cooling fans , each of the cooling fans corresponding to one of the computing nodes to provide air cooling to the corresponding computing node; a coolant distribution unit, CDU, coupled to each of the computing nodes to provide liquid cooling to a corresponding processor via a corresponding liquid cold plate, wherein the CDU includes a liquid pump to provide cooling liquid to remove heat generated from the processor of each computing node; and a rack management controller, RMC, coupled to the CDU , the cooling fans , and the computing nodes (203 A, 203B, 203C, 203D, 203E), wherein the RMC is configured to: collect real-time operating data from each of the computing nodes (203 A, 203B, 203C, 203D, 203E), the cooling fans , and the CDU , perform an optimization using a predetermined optimization function to determine an optimal pump speed of the liquid pump and optimal fan speeds of the cooling fans based on the collected real-time operating data, such that an output of the optimization function representing a total power consumption of the liquid pump and the plurality of cooling fans reaches minimum, control a pump speed of the liquid pump based on the optimal pump speed, and control fan speeds of the cooling fans based on the optimal fan speeds corresponding to the cooling fans respectively. a plurality of computing nodes (203 A, 203B, 203C, 203D, 203E) arranged in a stack, each computing node containing at least one processor attached to a liquid cold plate ; a plurality of cooling fans , each of the cooling fans corresponding to one of the computing nodes to provide air cooling to the corresponding computing node; a coolant distribution unit, CDU, coupled to each of the computing nodes to provide liquid cooling to a corresponding processor via a corresponding liquid cold plate, wherein the CDU includes a liquid pump to provide cooling liquid to remove heat generated from the processor of each computing node; and a rack management controller, RMC, coupled to the CDU , the cooling fans , and the computing nodes (203 A, 203B, 203C, 203D, 203E), wherein the RMC is configured to: collect real-time operating data from each of the computing nodes (203 A, 203B, 203C, 203D, 203E), the cooling fans , and the CDU , perform an optimization using a predetermined optimization function to determine an optimal pump speed of the liquid pump and optimal fan speeds of the cooling fans based on the collected real-time operating data, such that an output of the optimization function representing a total power consumption of the liquid pump and the plurality of cooling fans reaches minimum, control a pump speed of the liquid pump based on the optimal pump speed, and control fan speeds of the cooling fans based on the optimal fan speeds corresponding to the cooling fans respectively. collect real-time operating data from each of the computing nodes (203 A, 203B, 203C, 203D, 203E), the cooling fans , and the CDU , perform an optimization using a predetermined optimization function to determine an optimal pump speed of the liquid pump and optimal fan speeds of the cooling fans based on the collected real-time operating data, such that an output of the optimization function representing a total power consumption of the liquid pump and the plurality of cooling fans reaches minimum, control a pump speed of the liquid pump based on the optimal pump speed, and control fan speeds of the cooling fans based on the optimal fan speeds corresponding to the cooling fans respectively. <EOS>