chipset(s), inefficiency in the power supply, and the memory. On thing that
surprised me a bit the last time I looked at this a year ago was that the
power use of typical memory sticks is quite high, often more than 10W. In
do your systems use very large numbers of dimms? I think ours are
typically 4-8. so even 8x10W is going to be comparable to a cpu
or the inefficiency of a mediocre PSU.
like most of these other factors, this is a situation that's improving -
one of ddr3's main changes is going from 1.8 to 1.5V, saving ~30% on power.
one nice thing is that dram dissipate a lot less power when fully-on
but not continuously bursting (~50 mA vs 300). I don't know whether current
bios/mem controllers will but dram into the really low-power modes (~7mA
self-refresh) by default.
fact if you look at system with well-designed cooling, you'll see that the
fans are designed to blow a lot of air over the memory area.
yes, though the power density is relatively low. I wonder if one could
come up with a specific access pattern that would overheat particular
chips on a dimm - perhaps even corresponding chips on a dual-rank dimm...
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