I always turn my monitors to the lowest possible brightness for long work sessions, so I assumed (perhaps mistakenly) that this eco mode would already be close

I always turn my monitors to the lowest possible brightness for long work sessions, so I assumed (perhaps mistakenly) that this eco mode would already be close to my settings out of the box, and if anything, too bright. Assuming 20c per kWh (California rates, mostly solar during the day) and one kWh per day (8h at 130kW average use), much higher than the allowed EU limit and the eco mode, the monetary cost comes down to about 4 USD per month. So definitely not negligible but also not a reason to avoid being able to tile 64 terminals if one wanted to do that. [edit: the above estimate is almost certainly an upper bound on the energy I would ever use myself with such an item; I would be curious to measure it properly if/when I upgrade to one, and curious if the OP has a measure of their own usage. My best guess is that in practice I would average between 2 and 3 kWh every week (2 USD/month) rather than 5 kWh, because I tend to work in low light.]