An Overdrive processor with FSB of 25MHz. This one can upgrade a 16MHz 486 to 48MHz, 20MHz to 60MHz and 25MHz to 75MHz.

As seen on the top of the picture this CPU has voltage regulators on it to transform the 5V from the motherboard to 3,3V for the CPU. The CPU inside has been made on a narrower manufacturing process and thus it needs less power. The idea of Overdrive is to upgrade old systems that often only provide 5V.