But rock it does. Northbridge heatsinks are designed for chips with large packages and/or integrated heat spreaders, more like 25mm square than 8mm square. With that much area, a 2-point mount is okay because there's no leverage to rock it. A small chip in the middle might as well be a single point fulcrum. It's super easy to upset.
We're already designing an improved heatsink (more dissipative surface area on the fins) with 4-point M3 screw mounting, like what's been working on our stickminers for most of the last decade. Might have samples in the next week.
Phil, I think yours went out before I started lapping the heatsink underside. The ones we got in were not exactly smooth either, and the smoother and flatter the mating surface, the better.
I haven’t experienced this uneven heatsink issue you mentioned. It kinda seems like you got a bad batch.
Four point mount custom heatsink with a thicker base will be awesome! There really isn’t any headroom anymore with the current one.
Ahh the joys of mass production. You might never see it but 10% of your boards could.
Board deflection of only 1% will cause this, even a .5% settling error of the asic will cause it. Maybe too much paste on asic pad.
More of a problem for Muti asic boards though