So I hit a snag with my build from earlier this summer. I apparently spent so much time worrying about whether the massive Noctua NH-D15 cooler was too tall to fit in the case (it fits, but it has at most a few mm to spare) that I neglected to consider whether it would actually fit properly on the motherboard (after all, the CPU area on a mATX board is the same size as on an ATX board, and surely no one would make a cooler that wouldn’t fit on standard size boards). Upon opening the cooler box, it became clear that this was a mistake, this thing is very wide (150mm). Sure enough checking their website:

Fortunately its not quite so bad as that. The heatsink, fans, and fan clips do make contact with the video card, but not so much that they cause significant deflection, and the back of the card is almost entirely heat spreader, and even that has a plastic sheet over it, so there’s not much chance of shorting it. Just to be safe I did a lackluster job using electrical tape to cover the bottom of the heatsink and fan clips.

Seems to have worked fine, though I’m a bit worried I might have to replace the cooler if I end up upgrading the video card down the line.

tl;dr: Actually pay attention to those compatibility matrices if you don’t want to look like a moron.