There was a Power Supply company a few years back that did this (I had one of them) I do not remember the company name but they were silent (had a massive heat sink). what they did was have a back plate that had all the connectors and you would sit the external power supply next to your computer...
I have see similar activity with other OS options. The problem for me at the time was actually the internet security program I was using (kaspersky). Now that was a few years ago and I don't use them any longer. But almost every computer I used their software on had speedtest and other download...
What I love about Corsair let me count the ways:
Stability.
Overclock-ability.
Reliability.
Functionality
The Versatility.
The Styles.
The Warranty.
Plus, many more benefits. Too many to list.
Plus, Got to love the Power supplies as I use them in server computers (the last one...
Could be hidden files like the Pagefile.sys, Hiberfil.sys (hibernation file). Also could be shadow copys (look at the drive properties and under Previous versions.. Also could be that the system restore is also using space.
If you run Virtual machines then I would say yes. or Lots of multitasking like running adobe Photoshop / video editing software and others while doing other stuff. Other than that it would not make any noticeable difference.