The power supply system for the front-end electronics of the HADES resistive plate chamber (RPC) detector, installed at GSI (Darmstadt, Germany), is described. The system has a distributed architecture that includes custom low-voltage boards using isolated DC-DC switching converters. These converters are compact and operate at high efficiency. The converters are fitted with input and output electromagnetic interference filters, resulting in very low output noise. Operational tests of the RPC detector demonstrate that the performance of the detector when powered by this system is comparable to that achieved when powered by laboratory bench supplies, proving its suitability for large-scale applications requiring time resolutions better than 100 ps.