3 ms·
Sure, the CPU may enter a power-saving state, but presumably for each box, there's a minimum level of power consumption for things like the motherboard, BMC, RA
by mwcampbell 5y ago
Sure, the CPU may enter a power-saving state, but presumably for each box, there's a minimum level of power consumption for things like the motherboard, BMC, RAM, and case fan(s). The reason why AWS bare-metal instances are absurdly expensive compared to OVH dedicated servers is that AWS packs more computing power into each box. So for each core and gigabyte of RAM, I would guess AWS is using less power (edit: especially when idle), because they don't have the overhead of lots of small boxes. Yet I can have one of those small boxes to myself for less than I'd have to pay for the equivalent computing power and bandwidth from AWS.
- zozbot234 5y agoInterestingly, I believe that unused DIMM modules could be powered down if the hardware bothered to support that. Linux has to support memory hotplug anyway because it's long been in use on mainframe platforms, so the basic OS-level support is there already. Since it's not being addressed in any way by hardware makers, my guess is that RAM power use in idle states is low enough that it basically doesn't matter.
- dijit 5y agoRAM uses the same amount of power under high load as low load due to the way it is constantly refreshing the contents. Each stick of DDR4 is going to consume on the order of 1.2w (idle CPUs can theoretically go lower than this). I’d rather shut a whole machine down than go to the effort of offlining individual DIMMs, since the consumption is so low and quite static.