Were the video drivers installed correctly? If it happened right after the Windows installation, there must be a software problem. It sometimes happens that the drivers get installed incorrectly, and you might need to delete the current ones and install the new drivers manually. It’s a little tricky, but it does work.
You can also try reinstalling Windows from the beginning one more time, hoping that helps. You can upgrade to a newer version and go, for instance, to Windows 10. There are a lot of possibilities to buy activation keys for windows 10 cheap online. The new OS might be better at controlling the RGB.
