Article about power consumption:
https://arstechnica.com/gadgets/2022/10/high-idle-power-use-on-intel-arc-gpus-requires-fiddling-with-bios-settings/
Users will need to go into their PC's BIOS and configure a pair of advanced PCI Express power management settings—the "Native ASPM" (or active-state power management) setting should be enabled, and the "PCI Express root port ASPM" setting should be enabled and set to "L1 Substates." You'll also need to set the PCI Express Link State Power Management setting to "maximum power savings" in Windows' advanced power options settings.
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Testing from Tom's Hardware shows that with the settings enabled, Arc A750 power consumption at idle dropped from 37.3 W to 15.5 W, a significant drop. The same settings didn't seem to have an effect on an Arc A770 card, though it's unclear whether this is a motherboard bug, a GPU hardware or firmware or driver problem, or something else.
Intel may be able to address the issue in the long-term with driver or firmware updates for the Arc A-series GPUs, but the troubleshooting article doesn't make it sound very likely. Intel says that the company "will be looking at making optimizations in future generations," which makes it sound like we'll need new hardware to address the issue decisively.