> I resorted to removing the power plug from the PC every evening after it kept turning itself on during the night semi-randomly. It was in "suspend to disk" mode, whatever that is in more technical power-save jargon terms, not just "suspend-to-ram".
In "Suspend to RAM", the RAM is kept powered when the computer is shut down, and thus doesn't have to be touched on wake, but it means the computer has to stay powered the whole time.
In "Suspend to disk", the entire RAM is written to disk (which can take some time especially with an HDD) then the computer shuts down entirely, on wake the OS will restore RAM from disk before resuming. The need to read data back from disk to RAM makes the wake costlier, but because everything's on disk the computer can be completely shutdown.
The two can be combined into mode where data is written to disk (making going to sleep slower) then the computer enters "suspend to RAM" mode. If the computer is resumed normally it is restored from RAM, but if the computers suffers power loss it's restored from disk. Either way the computer doesn't have to boot from scratch and all the working set should be recovered. IIRC it's the default behaviour for macOS laptops, microsoft calls it "hybrid sleep".