Two things you might want to look at . . .
Check your temp levels. Some motherboards have a utility that will allow you to monitor it live while you are in Windows, and that would be best. Lacking that, when it freezes, force a reboot and go into CMOS and check it there. Note that it will cool quickly, so it won't show you as high as it was.
Another, and more likely prospect, is an outdated or corrupted video driver. A characteristic of that is that yhou get no error message, and it just freezes