Starting with (I think) kernel-4.5.0-0.rc0.git5.1.fc24 I have been getting "freezes" with X. The laptop is still up and working, just the display completely freezes and has no updates. Sometimes it recovers after 20 seconds or so, sometimes it does not. Logging in remotely I see no messages in dmesg or /var/log/Xorg.0.log that happen when the freezes do. Running 'chvt' remotely or hitting control-alt-lf3 or the like has no effect either. The only thing that seems to bring things back is doing a suspend/resume. Happy to try and debug if there's some way to gather more info. I will confirm which kernel it started on at least...
Confirmed that kernel-4.5.0-0.rc0.git1.1.fc24.x86_64 doesn't have the issue. Will try others to isolate when it landed.
And after digging around some more and rebooting a bunch, it looks like this might have been a mesa bug. The update today seems to fix it up or at least make it much less likely. Sorry for the noise. :)