All electrolytic capacitors have a limited lifespan. Eventually the electrolyte dries out and deteriorates. After that they may overheat when voltage is applied, which may cause them to expel electrolyte onto the board or even explode (pop!). These pics look like maybe leaked electrolyte on the SMT bits next to the electrolytic caps. The most obvious indicators of a failed electro are leaked black goo or a bulging container. Electros generally have the cylindrical can shape.
Several years ago there, was a Chinese company selling caps at a lower cost. Lots of manufacturers used their product, only to later discover that their (stolen) electrolyte formula was defective, causing wholesale motherboard failures. Several motherboard makers went out of business, as consequence, just from warranty repair costs. I had one such MB, which worked fine after replacing the caps. Turns out, the caps were cheaper because they had, unknowingly, left out an essential ingredient.
