To understand why Windows 10 shows CAM.Desktop.exe using a large amount of data, it is useful to look at how the current version of CAM works.
With the release of version 3.7.x, CAM was split into two applications: CAM.exe and CAM.Desktop.exe, separating the core CAM functions of hardware control and monitoring from the user interface. Here’s a screenshot of Task Manager where you can see both CAM.exe and CAM.Desktop.exe running:
Note: You see multiple versions of CAM.exe because it is running multiple processes by design. There is not a problem with CAM or your system.
The CAM desktop application--the user interface to CAM--was developed using a cross-platform application framework called ElectronJS. As a consequence of using Electron, the CAM.Desktop.exe is actually a self-contained, Chromium-based browser that is connected specifically to the CAM core using a network connection called localhost (in networking, localhost means this computer, as opposed to a web server located on a different computer). The CAM desktop and core applications communicate with one another using network data packets and protocols through the localhost interface on your computer (for the technically inclined, the specific address used is localhost:38517).
Per the standards governing network behavior, any packets sent to the localhost interface are connected at the link layer in the network stack. They are never passed to a network interface controller or hardware device driver and cannot appear on the network outside the computer itself. This means the data packets moving between the core CAM application and the desktop application are contained only in your system.
Unfortunately, Microsoft’s Data Usage tool does not differentiate packet traffic on the localhost interface from data packets that are actually passed to the network. By tracking all of the data packets that are sent through the network stack, including those on the localhost interface, Microsoft sees a very large amount of data usage even when those packets are simply being passed between the two applications.
How much data does CAM actually send to its servers?
In terms of data that’s actually sent from your computer to the CAM servers, it is usually no more than ~500MB a month with FPS overlay and game tracking enabled. With FPS overlay disabled, it would be lower than this.
If you are running CAM in Guest mode, about ~1.7 KB of system profile data and 1 ~KB of login data per month would be sent to the CAM servers. This would change if you log in and out frequently, but the amount of data would still be quite small.