Does the USB 3.0 stick, when mounted in a rear panel 3.0 slot, still access RAM for the purpose of being able to put OMV4 into a Wake On LAN scenario?
depends on the sleep mode. suspend to ram would but suspend to disk would write the contents of ram to your usb stick (not good for life). The usb version doesn't make a different. If you are going to suspend your OMV system, I would first look at arm devices because you are really concerned about energy. If they can't do what you want, don't use a usb stick on an amd64 system. Use an ssd or hard drive.