[mmf]

As I did not have the numbers fresh in memory (apparently I needed a refresh ;) ) I googled for dram data sheet and got the first ddr3 PDF (Hynix). Quick, and very dirty math suggests that

-refresh power is on the order of milliwats per Gigabyte

-memory access is on the order of 0.1W per GB per second

For refresh power, let's face it: it's puny. Regarding the active power, I have yet to see anything (off chip and this size) that is better than that.

P.S. I did say active in my original post :)

[codebook]

you overlooked refresh time, which is around 7~8 ms. So, in order to keep the DRAM data alive, DRAM should consume a few tenths of Watt per Gigabyte per second, it is considerable amount of power.

[mmf]

A few corrections:

-refresh period is more like 32-64ms

-refreshing is way (way) cheaper than streaming data out since you refresh an entire word line, and you do not pay io cost, which is a significant fraction of the cost of accessing dram.

[witty_username]

watt per second makes little sense in this context

watt != energy

[mmf]

It's W/GBps, or if you prefer simplifying J/GB. I like the former better, power and bandwidth are handier in real life computer science.

[witty_username]

Ah, it made sense now.

[dooptroop]

But Watt * second IS energy.