A heat dissipation device is used to dissipate heat generated by a number of memory chips of a motherboard. The heat dissipation device includes two brackets attached to the motherboard and at opposite sides of the memory chips, are a support, and a fan. The support includes a fixing plate and two clamping plates extending from opposite ends of the fixing plate. The clamping plates are rotatably mounted to the brackets, and are positioned above the memory chips. The fan is sandwiched between the clamping plates or mounted to the fixing plate.