On Monday, November 5, 2018 at 4:15:04 PM UTC+8, Paul wrote:

The hottest memories were RAMBUS. But there was a
reason for that. Each memory chip was sufficient to
answer all queries. You could "focus" your query
on a single chip on a RAMBUS RIMM, and that chip
would get hot because of the *4W* power dissipation.
The other seven chips in the "rank" would remain
cool by comparison. It is because of this "hot chip"
situation, only on RAMBUS, that RAMBUS RIMMs had
heatsinks *riveted* to the DIMM. So a user could
not remove the heatsink, and cause a chip to smoke.
The metal cover was as much a heat spreader, as
a chip cooler.

The memories we use now, don't do that. All chips
rise to the same temperature in a rank (assumes normal
random computer patterns). The cooler is there to
cool all the chips, rather than spread the heat
away from a single hot chip. As a result, the
cooler plates are not riveted. A user can remove
them if they want.

I saw a recent reference to this topic again,
perhaps on some server motherboards. But the concept
has been around long enough, I no longer pay attention
to such articles.

Paul

I presume server ECC FBDIMMs run hotter - I have seen pizza boxes with fans
directed over the memory modules.