Heatsink and heatsink-positioning system

A heatsink-positioning system comprising:

• a heatsink, comprising:
• a circular flat plate;
• a sidewall, connecting to the circular flat plate, extending away from the circular flat plate, and having a plurality of non-planar portions and a plurality of planar regions, and the planar regions are orthogonal to the radial directions of the circular flat plate, wherein the distances between each of the planar regions and the center of the circular flat plate are substantially equal;
• and
• a plurality of equally spaced foot portions, connecting to the sidewall and extending away from the sidewall, the plurality of foot portions each having a first side and second side opposite the first side, wherein one of the non-planar portions extends away from one of the first and second sides of each foot portion, and wherein one of the planar regions is disposed between and bounded by two non-planar portions extending from two adjacent foot portions;
• and
• a positioning device, having a plurality of positioning planes corresponding to the planar regions, wherein at least two of the planar regions are parallel to at least two of the positioning planes, and the at least two of the planar regions and the at least two of the positioning planes contact and engage each other by surface contact, so that the heatsink is fixed by the positioning device.