1. A workload dispatch device, comprising: a monitor, being configured to monitor operating conditions of a plurality of servers; a processor electrically connected to the monitor, being configured to execute the following operations: creating an average performance index table for a plurality of algorithms according to the operating conditions of the servers; normalizing the average performance index table; calculating a benchmark for each of the algorithms according to the normalized performance index table and a corresponding weighting table; and choosing a candidate algorithm from the algorithms according to the benchmarks; and a dispatcher electrically connected to the processor, being configured to dispatch a workload to the servers according to the candidate algorithm, wherein the benchmark for each of the algorithms is a sum of products of each of a plurality of reference values in the normalized performance index value multiplied with a corresponding one of a plurality of weights in the weighting table.