I've a cheapo eBuyer Value router/modem that works fine, excellent spec, but the smoothing cap on the on-board power circuit gets stinking hot. System runs from a 9V AC wall-wart, bridge rectifier and smoothing on board before 5V and 3.3V regulators, both low drop-out types. The original was a 1000uF, 16V 105C type, no-name brand, and I found it bulged and leaking when I opened the box a few months after buying it. Swapped it for a larger 1000uF 25V 105C no-name - gets too hot to touch for more than a few seconds. Started running the device on 9V DC input (a SMPS wart), which will lose about 1.2V going through the bridge, still plenty of overhead for the regs. The cap is a bit cooler but still hot. Swapped again for an even bigger 1000uF 35V 105C Dubilier with 100n ceramic across it for good luck, still too hot to touch for long. Why does it get hot on an already smooth DC input? Do the bigger motherboard caps also run hot?