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Comment by stefan_ | Hacker News Reader

Is selective power off for individual DIMMs a thing? Not sure I want the power consumption of 128GB when I don't need it.

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I don't think so, unless you own an IBM mainframe that allows you to hot swap even CPUs (as long as you disable them first and allow the OS to migrate threads to others).

Does more RAM use more power?

Yes, DRAM cells have to be refreshed every 60 ms or so. More RAM means more cells to refresh which means more power consumption.

Yes, although if we're talking about improvements in RAM density (lithography improvements) rather than just putting more equivalent RAM in a machine, then that tends to mean lower power consumption per bit.

It should, since the banks need to be constantly refreshed. I think the bigger power consumption for standby phones is RAM.

> I think the bigger power consumption for standby phones is RAM.

Looking at this analysis, it seems the cellular radio is the largest consumer of power in standby, with RAM being minimal:

https://www.usenix.org/legacy/event/atc10/tech/full_papers/C...

It looks like you are correct. I wasn't truly sure of that statement when I made it. It was just mis-remembering something heard in the lecture here[1] and somehow I formed the idea that RAM is a big consumer in standby mode (even though the lecturer did not make such a claim)

[1] https://youtu.be/wHVyshkyZ4w?t=1h20m44s

SRAM (not DRAM).

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