Patent ID: 8553415

Claim:
An electronic device comprising: a casing defining a plurality of through holes therein, the casing comprises a base and a side plate extending from a laterally side of the base, the side plate defining the plurality of through holes therein, the plurality of through holes comprising a plurality of first through holes and a plurality of second through holes, a width of each of the plurality of second through holes being larger than a width of each of the plurality of first through holes; a fan defining an air outlet at one side thereof facing the through holes of the casing, the air outlet comprising a first portion and a second portion, air pressure in the first portion being larger than air pressure of the second portion; and a heat sink being located at the air outlet of the fan, the heat sink comprising a first fin set arranged on the first portion and a second fin set arranged on the second portion, the first fin set comprising a plurality of first fins stacked together, a first passage being defined between each of two neighboring first fins, the second fin set comprising a plurality of second fins stacked together, a second passage being defined between each of two neighboring second fins, a width of the second passage being less than a width of the first passage, wherein each first passage communicates with the first through holes, and each second passage communicates with the second through holes, and wherein each first passage is aligned only with the first through holes, and each second passage is aligned only with the second through holes.