Rekordbox is probably not the only software installed - Windows comes with a bunch of pre-installed software, and depending on where you bought the system there may be other software that came pre-installed (AV software very commonly).
If you run the logging tools we can take a deeper look, but if you'd prefer not to probably the best we can do is advise you to reinstall Windows, make sure any drivers and BIOS are up to date, and see if that resolves it.