This card is known to have issues with the memory heat sinks falling off . That is, for the first revision of this model (1.01). The heat sinks are held to the chips by some sort of tape, there are no screws.
Actually, on the images above, one of the heat sinks is missing, wonder why...

What's strange is that there are holes and an outline for the heat sink, but they do not correspond to the heat sinks that are actually in place.

The other revisions 1.02 and 1.03 have better memory heat sinks, that are screwed into place (and follow the outline on the card, how convenient!).