Provided is a heat exchanger, heat sink or coldwall having a machined manifold for receiving a plurality of individual, modular micro-channel heat exchanger elements. The manifold further includes a parallel flow network or flow distribution network for distributing a cooling fluid uniformly to all micro-channel heat exchanger elements. Each micro-channel heat exchanger element is individually manufactured and tested prior to integration with the manifold. The design of the micro-channel heat exchanger elements may include a straight fin, a high density fin, lanced offset fin, and perforated offset layers fin configurations.